text: # -*- coding: utf-8 -*-
  from collections import OrderedDict, defaultdict
  import copy
  from functools import partial, reduce
  import inspect
  import logging
  
  from six import string_types
  
  from ..core import State, Machine, Transition, Event, listify, MachineError, Enum, EnumMeta, EventData
  
  _LOGGER = logging.getLogger(__name__)
  _LOGGER.addHandler(logging.NullHandler())
  
  # this is a workaround for dill issues when partials and super is used in conjunction
  # without it, Python 3.0 - 3.3 will not support pickling
  # https://github.com/pytransitions/transitions/issues/236
  _super = super
  
  
  # converts a hierarchical tree into a list of current states
  def _build_state_list(state_tree, separator, prefix=[]):
      res = []
      for key, value in state_tree.items():
          if value:
              res.append(_build_state_list(value, separator, prefix=prefix + [key]))
          else:
              res.append(separator.join(prefix + [key]))
      return res if len(res) > 1 else res[0]
  
  
  # custom breadth-first tree exploration
  # makes sure that ALL children are evaluated before parents in parallel states
  def _resolve_order(state_tree):
      s = state_tree
      q = []
      res = []
      p = []
      while True:
          for k in reversed(list(s.keys())):
              pk = p + [k]
              res.append(pk)
              if s[k]:
                  q.append((pk, s[k]))
          if not q:
              break
          p, s = q.pop(0)
      return reversed(res)
  
  
  class FunctionWrapper(object):
      """ A wrapper to enable transitions' convenience function to_<state> for nested states.
          This allows to call model.to_A.s1.C() in case a custom separator has been chosen."""
      def __init__(self, func, path):
          """
          Args:
              func: Function to be called at the end of the path.
              path: If path is an empty string, assign function
          """
          if path:
              self.add(func, path)
              self._func = None
          else:
              self._func = func
  
      def add(self, func, path):
          """ Assigns a `FunctionWrapper` as an attribute named like the next segment of the substates
              path.
          Args:
              func (callable): Function to be called at the end of the path.
              path (string): Remaining segment of the substate path.
          """
          if path:
              name = path[0]
              if name[0].isdigit():
                  name = 's' + name
              if hasattr(self, name):
                  getattr(self, name).add(func, path[1:])
              else:
                  setattr(self, name, FunctionWrapper(func, path[1:]))
          else:
              self._func = func
  
      def __call__(self, *args, **kwargs):
          return self._func(*args, **kwargs)
  
  
  class NestedEvent(Event):
      """ An event type to work with nested states.
          This subclass is NOT compatible with simple Machine instances.
      """
  
      def trigger(self, _model, _machine, *args, **kwargs):
          """ Serially execute all transitions that match the current state,
          halting as soon as one successfully completes. NOTE: This should only
          be called by HierarchicalMachine instances.
          Args:
              _model (object): model object to
              _machine (HierarchicalMachine): Since NestedEvents can be used in multiple machine instances, this one
                                              will be used to determine the current state separator.
              args and kwargs: Optional positional or named arguments that will
                  be passed onto the EventData object, enabling arbitrary state
                  information to be passed on to downstream triggered functions.
          Returns: boolean indicating whether or not a transition was
              successfully executed (True if successful, False if not).
          """
          func = partial(self._trigger, _model, _machine, *args, **kwargs)
          # pylint: disable=protected-access
          # noinspection PyProtectedMember
          # Machine._process should not be called somewhere else. That's why it should not be exposed
          # to Machine users.
          return _machine._process(func)
  
      def _trigger(self, _model, _machine, *args, **kwargs):
          state_tree = _machine._build_state_tree(getattr(_model, _machine.model_attribute), _machine.state_cls.separator)
          state_tree = reduce(dict.get, _machine.get_global_name(join=False), state_tree)
          ordered_states = _resolve_order(state_tree)
          done = set()
          res = None
          for state_path in ordered_states:
              state_name = _machine.state_cls.separator.join(state_path)
              if state_name not in done and state_name in self.transitions:
                  state = _machine.get_state(state_name)
                  event_data = EventData(state, self, _machine, _model, args=args, kwargs=kwargs)
                  event_data.source_name = state_name
                  event_data.source_path = copy.copy(state_path)
                  res = self._process(event_data)
                  if res:
                      elems = state_path
                      while elems:
                          done.add(_machine.state_cls.separator.join(elems))
                          elems.pop()
          return res
  
      def _process(self, event_data):
          machine = event_data.machine
          machine.callbacks(event_data.machine.prepare_event, event_data)
          _LOGGER.debug("%sExecuted machine preparation callbacks before conditions.", machine.name)
  
          try:
              for trans in self.transitions[event_data.source_name]:
                  event_data.transition = trans
                  if trans.execute(event_data):
                      event_data.result = True
                      break
          except Exception as err:
              event_data.error = err
              raise
          finally:
              machine.callbacks(machine.finalize_event, event_data)
              _LOGGER.debug("%sExecuted machine finalize callbacks", machine.name)
          return event_data.result
  
  
  class NestedState(State):
      """ A state which allows substates.
      Attributes:
          states (OrderedDict): A list of substates of the current state.
          events (dict): A list of events defined for the nested state.
          initial (str): Name of a child which should be entered when the state is entered.
          exit_stack (defaultdict): A list of currently active substates
      """
  
      separator = '_'
      u""" Separator between the names of parent and child states. In case '_' is required for
          naming state, this value can be set to other values such as '.' or even unicode characters
          such as '↦' (limited to Python 3 though).
      """
  
      def __init__(self, name, on_enter=None, on_exit=None, ignore_invalid_triggers=None, initial=None):
          _super(NestedState, self).__init__(name=name, on_enter=on_enter, on_exit=on_exit,
                                             ignore_invalid_triggers=ignore_invalid_triggers)
          self.initial = initial
          self.events = {}
          self.states = OrderedDict()
          self._scope = []
  
      def add_substate(self, state):
          """ Adds a state as a substate.
          Args:
              state (NestedState): State to add to the current state.
          """
          self.add_substates(state)
  
      def add_substates(self, states):
          """ Adds a list of states to the current state.
          Args:
              states (list): List of states to add to the current state.
          """
          for state in listify(states):
              self.states[state.name] = state
  
      def scoped_enter(self, event_data, scope=[]):
          self._scope = scope
          try:
              self.enter(event_data)
          finally:
              self._scope = []
  
      def scoped_exit(self, event_data, scope=[]):
          self._scope = scope
          try:
              self.exit(event_data)
          finally:
              self._scope = []
  
      @property
      def name(self):
          return self.separator.join(self._scope + [_super(NestedState, self).name])
  
  
  class NestedTransition(Transition):
      """ A transition which handles entering and leaving nested states.
  
      Attributes:
          source (str): Source state of the transition.
          dest (str): Destination state of the transition.
          prepare (list): Callbacks executed before conditions checks.
          conditions (list): Callbacks evaluated to determine if
              the transition should be executed.
          before (list): Callbacks executed before the transition is executed
              but only if condition checks have been successful.
          after (list): Callbacks executed after the transition is executed
              but only if condition checks have been successful.
      """
  
      def _resolve_transition(self, event_data):
          machine = event_data.machine
          dst_name_path = machine.get_local_name(self.dest, join=False)
          _ = machine.get_state(dst_name_path)
          model_states = listify(getattr(event_data.model, machine.model_attribute))
          state_tree = machine._build_state_tree(model_states, machine.state_cls.separator)
  
          scope = machine.get_global_name(join=False)
          src_name_path = event_data.source_path
          if src_name_path == dst_name_path:
              root = src_name_path[:-1]  # exit and enter the same state
              dst_name_path = dst_name_path[-1:]
          else:
              root = []
              while dst_name_path and src_name_path and src_name_path[0] == dst_name_path[0]:
                  root.append(src_name_path.pop(0))
                  dst_name_path.pop(0)
  
          scoped_tree = reduce(dict.get, scope + root, state_tree)
          exit_partials = [partial(machine.get_state(root + state_name).scoped_exit,
                                   event_data, scope + root + state_name[:-1])
                           for state_name in _resolve_order(scoped_tree)]
          if dst_name_path:
              new_states, enter_partials = self._enter_nested(root, dst_name_path, scope + root, event_data)
          else:
              new_states, enter_partials = {}, []
  
          scoped_tree.clear()
          for new_key, value in new_states.items():
              scoped_tree[new_key] = value
              break
  
          return state_tree, exit_partials, enter_partials
  
      def _change_state(self, event_data):
          state_tree, exit_partials, enter_partials = self._resolve_transition(event_data)
          for func in exit_partials:
              func()
          self._update_model(event_data, state_tree)
          for func in enter_partials:
              func()
  
      def _enter_nested(self, root, dest, prefix_path, event_data):
          if root:
              state_name = root.pop(0)
              with event_data.machine(state_name):
                  return self._enter_nested(root, dest, prefix_path, event_data)
          elif dest:
              new_states = OrderedDict()
              state_name = dest.pop(0)
              with event_data.machine(state_name):
                  new_states[state_name], new_enter = self._enter_nested([], dest, prefix_path + [state_name], event_data)
                  enter_partials = [partial(event_data.machine.scoped.scoped_enter, event_data, prefix_path)] + new_enter
              return new_states, enter_partials
          elif event_data.machine.scoped.initial:
              new_states = OrderedDict()
              enter_partials = []
              q = []
              prefix = prefix_path
              scoped_tree = new_states
              initial_names = [i.name if hasattr(i, 'name') else i for i in listify(event_data.machine.scoped.initial)]
              initial_states = [event_data.machine.scoped.states[n] for n in initial_names]
              while True:
                  event_data.scope = prefix
                  for state in initial_states:
                      enter_partials.append(partial(state.scoped_enter, event_data, prefix))
                      scoped_tree[state.name] = OrderedDict()
                      if state.initial:
                          q.append((scoped_tree[state.name], prefix + [state.name],
                                    [state.states[i.name] if hasattr(i, 'name') else state.states[i] for i in listify(state.initial)]))
                  if not q:
                      break
                  scoped_tree, prefix, initial_states = q.pop(0)
              return new_states, enter_partials
          else:
              return {}, []
  
      @staticmethod
      def _update_model(event_data, tree):
          model_states = _build_state_list(tree, event_data.machine.state_cls.separator)
          with event_data.machine():
              event_data.machine.set_state(model_states, event_data.model)
              states = event_data.machine.get_states(listify(model_states))
              event_data.state = states[0] if len(states) == 1 else states
  
      # Prevent deep copying of callback lists since these include either references to callable or
      # strings. Deep copying a method reference would lead to the creation of an entire new (model) object
      # (see https://github.com/pytransitions/transitions/issues/248)
      def __deepcopy__(self, memo):
          cls = self.__class__
          result = cls.__new__(cls)
          memo[id(self)] = result
          for key, value in self.__dict__.items():
              if key in cls.dynamic_methods:
                  setattr(result, key, copy.copy(value))
              else:
                  setattr(result, key, copy.deepcopy(value, memo))
          return result
  
  
  class HierarchicalMachine(Machine):
      """ Extends transitions.core.Machine by capabilities to handle nested states.
          A hierarchical machine REQUIRES NestedStates (or any subclass of it) to operate.
      """
  
      state_cls = NestedState
      transition_cls = NestedTransition
      event_cls = NestedEvent
  
      def __init__(self, *args, **kwargs):
          assert issubclass(self.state_cls, NestedState)
          assert issubclass(self.event_cls, NestedEvent)
          assert issubclass(self.transition_cls, NestedTransition)
          self._stack = []
          self.scoped = self
          _super(HierarchicalMachine, self).__init__(*args, **kwargs)
  
      def __call__(self, to_scope=None):
          if isinstance(to_scope, string_types):
              state_name = to_scope.split(self.state_cls.separator)[0]
              state = self.states[state_name]
              to_scope = (state, state.states, state.events)
          elif isinstance(to_scope, Enum):
              state = self.states[to_scope.name]
              to_scope = (state, state.states, state.events)
          elif to_scope is None:
              if self._stack:
                  to_scope = self._stack[0]
              else:
                  to_scope = (self, self.states, self.events)
          self._next_scope = to_scope
  
          return self
  
      def __enter__(self):
          self._stack.append((self.scoped, self.states, self.events))
          self.scoped, self.states, self.events = self._next_scope
          self._next_scope = None
  
      def __exit__(self, exc_type, exc_val, exc_tb):
          self.scoped, self.states, self.events = self._stack.pop()
  
      def add_model(self, model, initial=None):
          """ Extends transitions.core.Machine.add_model by applying a custom 'to' function to
              the added model.
          """
          models = [mod if mod != 'self' else self for mod in listify(model)]
          _super(HierarchicalMachine, self).add_model(models, initial=initial)
          initial_name = getattr(models[0], self.model_attribute)
          if hasattr(initial_name, 'name'):
              initial_name = initial_name.name
          # initial states set by add_model or machine might contain initial states themselves.
          if isinstance(initial_name, string_types):
              initial_states = self._resolve_initial(models, initial_name.split(self.state_cls.separator))
          # when initial is set to a (parallel) state, we accept it as it is
          else:
              initial_states = initial_name
          for mod in models:
              self.set_state(initial_states, mod)
              if hasattr(mod, 'to'):
                  _LOGGER.warning("%sModel already has a 'to'-method. It will NOT "
                                  "be overwritten by NestedMachine", self.name)
              else:
                  to_func = partial(self.to_state, mod)
                  setattr(mod, 'to', to_func)
  
      @property
      def initial(self):
          """ Return the initial state. """
          return self._initial
  
      @initial.setter
      def initial(self, value):
          self._initial = self._recursive_initial(value)
  
      def add_ordered_transitions(self, states=None, trigger='next_state',
                                  loop=True, loop_includes_initial=True,
                                  conditions=None, unless=None, before=None,
                                  after=None, prepare=None, **kwargs):
          if states is None:
              states = self.get_nested_state_names()
          _super(HierarchicalMachine, self).add_ordered_transitions(states=states, trigger=trigger, loop=loop,
                                                                    loop_includes_initial=loop_includes_initial,
                                                                    conditions=conditions,
                                                                    unless=unless, before=before, after=after,
                                                                    prepare=prepare, **kwargs)
  
      def add_states(self, states, on_enter=None, on_exit=None, ignore_invalid_triggers=None, **kwargs):
          """ Add new nested state(s).
          Args:
              states (list, str, dict, Enum or NestedState): a list, a NestedState instance, the
                  name of a new state, an enumeration (member) or a dict with keywords to pass on to the
                  NestedState initializer. If a list, each element can be a string, NestedState or enumeration member.
              on_enter (str or list): callbacks to trigger when the state is
                  entered. Only valid if first argument is string.
              on_exit (str or list): callbacks to trigger when the state is
                  exited. Only valid if first argument is string.
              ignore_invalid_triggers: when True, any calls to trigger methods
                  that are not valid for the present state (e.g., calling an
                  a_to_b() trigger when the current state is c) will be silently
                  ignored rather than raising an invalid transition exception.
                  Note that this argument takes precedence over the same
                  argument defined at the Machine level, and is in turn
                  overridden by any ignore_invalid_triggers explicitly
                  passed in an individual state's initialization arguments.
              **kwargs additional keyword arguments used by state mixins.
          """
          remap = kwargs.pop('remap', None)
          ignore = self.ignore_invalid_triggers if ignore_invalid_triggers is None else ignore_invalid_triggers
  
          for state in listify(states):
              if isinstance(state, Enum):
                  if isinstance(state.value, EnumMeta):
                      state = {'name': state, 'children': state.value}
                  elif isinstance(state.value, dict):
                      state = dict(name=state, **state.value)
              if isinstance(state, string_types):
                  if remap is not None and state in remap:
                      return
                  domains = state.split(self.state_cls.separator, 1)
                  if len(domains) > 1:
                      try:
                          self.get_state(domains[0])
                      except ValueError:
                          self.add_state(domains[0], on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore_invalid_triggers, **kwargs)
                      with self(domains[0]):
                          self.add_states(domains[1], on_enter=on_enter, on_exit=on_exit, ignore_invalid_triggers=ignore_invalid_triggers, **kwargs)
                  else:
                      if state in self.states:
                          raise ValueError("State {0} cannot be added since it already exists.".format(state))
                      new_state = self._create_state(state, on_enter=on_enter, on_exit=on_exit,
                                                     ignore_invalid_triggers=ignore, **kwargs)
                      self.states[new_state.name] = new_state
                      self._init_state(new_state)
              elif isinstance(state, Enum):
                  if self.state_cls.separator in state.name:
                      raise ValueError("State '{0}' contains '{1}' which is used as state name separator. "
                                       "Consider changing the NestedState.separator to avoid this issue."
                                       "".format(state.name, self.state_cls.separator))
                  if remap is not None and state.name in remap:
                      return
                  new_state = self._create_state(state, on_enter=on_enter, on_exit=on_exit,
                                                 ignore_invalid_triggers=ignore, **kwargs)
                  if state.name in self.states:
                      raise ValueError("State {0} cannot be added since it already exists.".format(state.name))
                  self.states[new_state.name] = new_state
                  self._init_state(new_state)
              elif isinstance(state, dict):
                  if remap is not None and state['name'] in remap:
                      return
                  state = state.copy()  # prevent messing with the initially passed dict
                  remap = state.pop('remap', None)
                  if 'ignore_invalid_triggers' not in state:
                      state['ignore_invalid_triggers'] = ignore
                  state_children = state.pop('children', state.pop('states', []))
                  state_parallel = state.pop('parallel', [])
                  transitions = state.pop('transitions', [])
                  new_state = self._create_state(**state)
                  self.states[new_state.name] = new_state
                  self._init_state(new_state)
                  remapped_transitions = []
                  with self(new_state.name):
                      if state_parallel:
                          self.add_states(state_parallel, remap=remap, **kwargs)
                          new_state.initial = [s if isinstance(s, string_types) else s['name'] for s in state_parallel]
                      else:
                          self.add_states(state_children, remap=remap, **kwargs)
                      if remap is not None:
                          drop_event = []
                          for evt in self.events.values():
                              self.events[evt.name] = copy.copy(evt)
                          for trigger, event in self.events.items():
                              drop_source = []
                              event.transitions = copy.deepcopy(event.transitions)
                              for source_name, trans_source in event.transitions.items():
                                  if source_name in remap:
                                      drop_source.append(source_name)
                                      continue
                                  drop_trans = []
                                  for trans in trans_source:
                                      if trans.dest in remap:
                                          conditions, unless = [], []
                                          for cond in trans.conditions:
                                              # split a list in two lists based on the accessors (cond.target) truth value
                                              (unless, conditions)[cond.target].append(cond.func)
                                          remapped_transitions.append({
                                              'trigger': trigger,
                                              'source': new_state.name + self.state_cls.separator + trans.source,
                                              'dest': remap[trans.dest],
                                              'conditions': conditions,
                                              'unless': unless,
                                              'prepare': trans.prepare,
                                              'before': trans.before,
                                              'after': trans.after})
                                          drop_trans.append(trans)
                                  for t in drop_trans:
                                      trans_source.remove(t)
                                  if not trans_source:
                                      drop_source.append(source_name)
                              for s in drop_source:
                                  del event.transitions[s]
                              if not event.transitions:
                                  drop_event.append(trigger)
                          for e in drop_event:
                              del self.events[e]
                      if transitions:
                          self.add_transitions(transitions)
                  self.add_transitions(remapped_transitions)
              elif isinstance(state, NestedState):
                  if state.name in self.states:
                      raise ValueError("State {0} cannot be added since it already exists.".format(state.name))
                  self.states[state.name] = state
                  self._init_state(state)
              elif isinstance(state, Machine):
                  new_states = [s for s in state.states.values() if remap is None or s not in remap]
                  self.add_states(new_states)
                  for ev in state.events.values():
                      self.events[ev.name] = ev
                  if self.scoped.initial is None:
                      self.scoped.initial = state.initial
              elif isinstance(state, State) and not isinstance(state, NestedState):
                  raise ValueError("A passed state object must derive from NestedState! "
                                   "A default State object is not sufficient")
              else:
                  raise ValueError("Cannot add state of type {0}. ".format(type(state).__name__))
  
      def add_transition(self, trigger, source, dest, conditions=None,
                         unless=None, before=None, after=None, prepare=None, **kwargs):
          if source != self.wildcard_all:
              source = [self.state_cls.separator.join(self._get_enum_path(s)) if isinstance(s, Enum) else s
                        for s in listify(source)]
          if dest != self.wildcard_same:
              dest = self.state_cls.separator.join(self._get_enum_path(dest)) if isinstance(dest, Enum) else dest
          _super(HierarchicalMachine, self).add_transition(trigger, source, dest, conditions,
                                                           unless, before, after, prepare, **kwargs)
  
      def get_global_name(self, state=None, join=True):
          local_stack = [s[0] for s in self._stack] + [self.scoped]
          local_stack_start = len(local_stack) - local_stack[::-1].index(self)
          domains = [s.name for s in local_stack[local_stack_start:]]
          if state:
              state_name = state.name if hasattr(state, 'name') else state
              if state_name in self.states:
                  domains.append(state_name)
              else:
                  raise ValueError("State '{0}' not found in local states.".format(state))
          return self.state_cls.separator.join(domains) if join else domains
  
      def get_local_name(self, state_name, join=True):
          state_name = state_name.split(self.state_cls.separator)
          local_stack = [s[0] for s in self._stack] + [self.scoped]
          local_stack_start = len(local_stack) - local_stack[::-1].index(self)
          domains = [s.name for s in local_stack[local_stack_start:]]
          if domains and state_name and state_name[0] != domains[0]:
              return self.state_cls.separator.join(state_name) if join else state_name
          return self.state_cls.separator.join(state_name) if join else state_name
  
      def get_nested_state_names(self):
          ordered_states = []
          for state in self.states.values():
              ordered_states.append(self.get_global_name(state))
              with self(state.name):
                  ordered_states.extend(self.get_nested_state_names())
          return ordered_states
  
      def get_nested_transitions(self, trigger="", src_path=None, dest_path=None):
          if src_path and dest_path:
              src = self.state_cls.separator.join(src_path)
              dest = self.state_cls.separator.join(dest_path)
              transitions = _super(HierarchicalMachine, self).get_transitions(trigger, src, dest)
              if len(src_path) > 1 and len(dest_path) > 1:
                  with self(src_path[0]):
                      transitions.extend(self.get_nested_transitions(trigger, src_path[1:], dest_path[1:]))
          elif src_path:
              src = self.state_cls.separator.join(src_path)
              transitions = _super(HierarchicalMachine, self).get_transitions(trigger, src, "*")
              if len(src_path) > 1:
                  with self(src_path[0]):
                      transitions.extend(self.get_nested_transitions(trigger, src_path[1:], None))
          elif dest_path:
              dest = self.state_cls.separator.join(dest_path)
              transitions = _super(HierarchicalMachine, self).get_transitions(trigger, "*", dest)
              if len(dest_path) > 1:
                  for state_name in self.states:
                      with self(state_name):
                          transitions.extend(self.get_nested_transitions(trigger, None, dest_path[1:]))
          else:
              transitions = _super(HierarchicalMachine, self).get_transitions(trigger, "*", "*")
              for state_name in self.states:
                  with self(state_name):
                      transitions.extend(self.get_nested_transitions(trigger, None, None))
          return transitions
  
      def get_nested_triggers(self, src_path=None):
          if src_path:
              triggers = _super(HierarchicalMachine, self).get_triggers(self.state_cls.separator.join(src_path))
              if len(src_path) > 1 and src_path[0] in self.states:
                  with self(src_path[0]):
                      triggers.extend(self.get_nested_triggers(src_path[1:]))
          else:
              triggers = list(self.events.keys())
              for state_name in self.states:
                  with self(state_name):
                      triggers.extend(self.get_nested_triggers())
          return triggers
  
      def get_state(self, state, hint=None):
          """ Return the State instance with the passed name. """
          if isinstance(state, Enum):
              state = self._get_enum_path(state)
          elif isinstance(state, string_types):
              state = state.split(self.state_cls.separator)
          if not hint:
              state = copy.copy(state)
              hint = copy.copy(state)
          if len(state) > 1:
              child = state.pop(0)
              try:
                  with self(child):
                      return self.get_state(state, hint)
              except (KeyError, ValueError):
                  try:
                      with self():
                          state = self
                          for elem in hint:
                              state = state.states[elem]
                          return state
                  except KeyError:
                      raise ValueError("State '%s' is not a registered state." % self.state_cls.separator.join(hint))
          elif state[0] not in self.states:
              raise ValueError("State '%s' is not a registered state." % state)
          return self.states[state[0]]
  
      def get_states(self, states):
          res = []
          for state in states:
              if isinstance(state, list):
                  res.append(self.get_states(state))
              else:
                  res.append(self.get_state(state))
          return res
  
      def get_transitions(self, trigger="", source="*", dest="*", delegate=False):
          """ Return the transitions from the Machine.
          Args:
              trigger (str): Trigger name of the transition.
              source (str, State or Enum): Limits list to transitions from a certain state.
              dest (str, State or Enum): Limits list to transitions to a certain state.
              delegate (Optional[bool]): If True, consider delegations to parents of source
          """
          with self():
              source_path = [] if source == "*" \
                  else source.split(self.state_cls.separator) if isinstance(source, string_types) \
                  else self._get_enum_path(source) if isinstance(source, Enum) \
                  else self._get_state_path(source)
              dest_path = [] if dest == "*" \
                  else dest.split(self.state_cls.separator) if isinstance(dest, string_types) \
                  else self._get_enum_path(dest) if isinstance(dest, Enum) \
                  else self._get_state_path(dest)
              matches = self.get_nested_transitions(trigger, source_path, dest_path)
              # only consider delegations when source_path contains a nested state (len > 1)
              if delegate is False or len(source_path) < 2:
                  return matches
              source_path.pop()
              while source_path:
                  matches.extend(self.get_transitions(trigger,
                                                      source=self.state_cls.separator.join(source_path),
                                                      dest=dest))
                  source_path.pop()
              return matches
  
      def get_triggers(self, *args):
          """ Extends transitions.core.Machine.get_triggers to also include parent state triggers. """
          triggers = []
          with self():
              for state_name in args:
                  state_path = state_name.split(self.state_cls.separator)
                  if len(state_path) > 1:  # we only need to check substates when 'state_name' refers to a substate
                      with self(state_path[0]):
                          triggers.extend(self.get_nested_triggers(state_path[1:]))
                  while state_path:  # check all valid transitions for parent states
                      triggers.extend(_super(HierarchicalMachine, self).get_triggers(self.state_cls.separator.join(state_path)))
                      state_path.pop()
          return triggers
  
      def has_trigger(self, trigger, state=None):
          """ Check whether an event/trigger is known to the machine
          Args:
              trigger (str): Event/trigger name
              state (optional[NestedState]): Limits the recursive search to this state and its children
          Returns:
              bool: True if event is known and False otherwise
          """
  
          state = state or self
          return trigger in state.events or any([self.has_trigger(trigger, sta) for sta in state.states.values()])
  
      def is_state(self, state_name, model, allow_substates=False):
          current_name = getattr(model, self.model_attribute)
          if allow_substates:
              if isinstance(current_name, Enum):
                  current_name = self.state_cls.separator.join(self._get_enum_path(current_name))
              if isinstance(state_name, Enum):
                  state_name = self.state_cls.separator.join(self._get_enum_path(state_name))
              return current_name.startswith(state_name)
          return current_name == state_name
  
      def on_enter(self, state_name, callback):
          """ Helper function to add callbacks to states in case a custom state separator is used.
          Args:
              state_name (str): Name of the state
              callback (str or callable): Function to be called. Strings will be resolved to model functions.
          """
          self.get_state(state_name).add_callback('enter', callback)
  
      def on_exit(self, state_name, callback):
          """ Helper function to add callbacks to states in case a custom state separator is used.
          Args:
              state_name (str): Name of the state
              callback (str or callable): Function to be called. Strings will be resolved to model functions.
          """
          self.get_state(state_name).add_callback('exit', callback)
  
      def set_state(self, states, model=None):
          """ Set the current state.
          Args:
              states (list of str or Enum or State): value of state(s) to be set
              model (optional[object]): targeted model; if not set, all models will be set to 'state'
          """
          values = [self._set_state(value) for value in listify(states)]
          models = self.models if model is None else listify(model)
          for mod in models:
              setattr(mod, self.model_attribute, values if len(values) > 1 else values[0])
  
      def to_state(self, model, state_name, *args, **kwargs):
          """ Helper function to add go to states in case a custom state separator is used.
          Args:
              model (class): The model that should be used.
              state_name (str): Name of the destination state.
          """
  
          current_state = getattr(model, self.model_attribute)
          if isinstance(current_state, list):
              raise MachineError("Cannot use 'to_state' from parallel state")
  
          event = EventData(self.get_state(current_state), Event('to', self), self,
                            model, args=args, kwargs=kwargs)
          if isinstance(current_state, Enum):
              event.source_path = self._get_enum_path(current_state)
              event.source_name = self.state_cls.separator.join(event.source_path)
          else:
              event.source_name = current_state
              event.source_path = current_state.split(self.state_cls.separator)
          self._create_transition(event.source_name, state_name).execute(event)
  
      def trigger_event(self, _model, _trigger, *args, **kwargs):
          """ Processes events recursively and forwards arguments if suitable events are found.
          This function is usually bound to models with model and trigger arguments already
          resolved as a partial. Execution will halt when a nested transition has been executed
          successfully.
          Args:
              _model (object): targeted model
              _trigger (str): event name
              *args: positional parameters passed to the event and its callbacks
              **kwargs: keyword arguments passed to the event and its callbacks
          Returns:
              bool: whether a transition has been executed successfully
          Raises:
              MachineError: When no suitable transition could be found and ignore_invalid_trigger
                            is not True. Note that a transition which is not executed due to conditions
                            is still considered valid.
          """
          with self():
              res = self._trigger_event(_model, _trigger, None, *args, **kwargs)
          return self._check_event_result(res, _model, _trigger)
  
      def _add_model_to_state(self, state, model):
          name = self.get_global_name(state)
          if self.state_cls.separator == '_':
              value = state.value if isinstance(state.value, Enum) else name
              self._checked_assignment(model, 'is_%s' % name, partial(self.is_state, value, model))
              # Add dynamic method callbacks (enter/exit) if there are existing bound methods in the model
              # except if they are already mentioned in 'on_enter/exit' of the defined state
              for callback in self.state_cls.dynamic_methods:
                  method = "{0}_{1}".format(callback, name)
                  if hasattr(model, method) and inspect.ismethod(getattr(model, method)) and \
                          method not in getattr(state, callback):
                      state.add_callback(callback[3:], method)
          else:
              path = name.split(self.state_cls.separator)
              value = state.value if isinstance(state.value, Enum) else name
              trig_func = partial(self.is_state, value, model)
              if hasattr(model, 'is_' + path[0]):
                  getattr(model, 'is_' + path[0]).add(trig_func, path[1:])
              else:
                  self._checked_assignment(model, 'is_' + path[0], FunctionWrapper(trig_func, path[1:]))
          with self(state.name):
              for event in self.events.values():
                  if not hasattr(model, event.name):
                      self._add_trigger_to_model(event.name, model)
              for state in self.states.values():
                  self._add_model_to_state(state, model)
  
      def _add_trigger_to_model(self, trigger, model):
          trig_func = partial(self.trigger_event, model, trigger)
          # FunctionWrappers are only necessary if a custom separator is used
          if trigger.startswith('to_') and self.state_cls.separator != '_':
              path = trigger[3:].split(self.state_cls.separator)
              if hasattr(model, 'to_' + path[0]):
                  # add path to existing function wrapper
                  getattr(model, 'to_' + path[0]).add(trig_func, path[1:])
              else:
                  # create a new function wrapper
                  self._checked_assignment(model, 'to_' + path[0], FunctionWrapper(trig_func, path[1:]))
          else:
              self._checked_assignment(model, trigger, trig_func)
  
      # converts a list of current states into a hierarchical state tree
      def _build_state_tree(self, model_states, separator, tree=None):
          tree = tree if tree is not None else OrderedDict()
          if isinstance(model_states, list):
              for state in model_states:
                  _ = self._build_state_tree(state, separator, tree)
          else:
              tmp = tree
              if isinstance(model_states, (Enum, EnumMeta)):
                  with self():
                      path = self._get_enum_path(model_states)
              else:
                  path = model_states.split(separator)
              for elem in path:
                  tmp = tmp.setdefault(elem.name if hasattr(elem, 'name') else elem, OrderedDict())
          return tree
  
      def _get_enum_path(self, enum_state, prefix=[]):
          if enum_state.name in self.states and self.states[enum_state.name].value == enum_state:
              return prefix + [enum_state.name]
          for name in self.states:
              with self(name):
                  res = self._get_enum_path(enum_state, prefix=prefix + [name])
                  if res:
                      return res
          return []
  
      def _get_state_path(self, state, prefix=[]):
          if state in self.states.values():
              return prefix + [state.name]
          for name in self.states:
              with self(name):
                  res = self._get_state_path(state, prefix=prefix + [name])
                  if res:
                      return res
          return []
  
      def _check_event_result(self, res, model, trigger):
          if res is None:
              state_names = getattr(model, self.model_attribute)
              msg = "%sCan't trigger event '%s' from state(s) %s!" % (self.name, trigger, state_names)
              for state_name in listify(state_names):
                  state = self.get_state(state_name)
                  ignore = state.ignore_invalid_triggers if state.ignore_invalid_triggers is not None \
                      else self.ignore_invalid_triggers
                  if not ignore:
                      # determine whether a MachineError (valid event but invalid state) ...
                      if self.has_trigger(trigger):
                          raise MachineError(msg)
                      # or AttributeError (invalid event) is appropriate
                      else:
                          raise AttributeError("Do not know event named '%s'." % trigger)
              _LOGGER.warning(msg)
              res = False
          return res
  
      def _get_trigger(self, model, trigger_name, *args, **kwargs):
          """Convenience function added to the model to trigger events by name.
          Args:
              model (object): Model with assigned event trigger.
              trigger_name (str): Name of the trigger to be called.
              *args: Variable length argument list which is passed to the triggered event.
              **kwargs: Arbitrary keyword arguments which is passed to the triggered event.
          Returns:
              bool: True if a transitions has been conducted or the trigger event has been queued.
          """
          return self.trigger_event(model, trigger_name, *args, **kwargs)
  
      def _has_state(self, state, raise_error=False):
          """ This function
          Args:
              state (NestedState): state to be tested
              raise_error (bool): whether ValueError should be raised when the state
                                  is not registered
         Returns:
              bool: Whether state is registered in the machine
          Raises:
              ValueError: When raise_error is True and state is not registered
          """
          found = _super(HierarchicalMachine, self)._has_state(state)
          if not found:
              for a_state in self.states:
                  with self(a_state):
                      if self._has_state(state):
                          return True
          if not found and raise_error:
              msg = 'State %s has not been added to the machine' % (state.name if hasattr(state, 'name') else state)
              raise ValueError(msg)
          return found
  
      def _init_state(self, state):
          for model in self.models:
              self._add_model_to_state(state, model)
          if self.auto_transitions:
              state_name = self.get_global_name(state.name)
              parent = state_name.split(self.state_cls.separator, 1)
              with self():
                  for a_state in self.get_nested_state_names():
                      if a_state == parent[0]:
                          self.add_transition('to_%s' % state_name, self.wildcard_all, state_name)
                      elif len(parent) == 1:
                          self.add_transition('to_%s' % a_state, state_name, a_state)
          with self(state.name):
              for substate in self.states.values():
                  self._init_state(substate)
  
      def _recursive_initial(self, value):
          if isinstance(value, string_types):
              path = value.split(self.state_cls.separator, 1)
              if len(path) > 1:
                  state_name, suffix = path
                  # make sure the passed state has been created already
                  _super(HierarchicalMachine, self.__class__).initial.fset(self, state_name)
                  with self(state_name):
                      self.initial = suffix
                      self._initial = state_name + self.state_cls.separator + self._initial
              else:
                  _super(HierarchicalMachine, self.__class__).initial.fset(self, value)
          elif isinstance(value, (list, tuple)):
              return [self._recursive_initial(v) for v in value]
          else:
              _super(HierarchicalMachine, self.__class__).initial.fset(self, value)
          return self._initial[0] if isinstance(self._initial, list) and len(self._initial) == 1 else self._initial
  
      def _resolve_initial(self, models, state_name_path, prefix=[]):
          if state_name_path:
              state_name = state_name_path.pop(0)
              with self(state_name):
                  return self._resolve_initial(models, state_name_path, prefix=prefix + [state_name])
          if self.scoped.initial:
              entered_states = []
              for initial_state_name in listify(self.scoped.initial):
                  with self(initial_state_name):
                      entered_states.append(self._resolve_initial(models, [], prefix=prefix + [self.scoped.name]))
              return entered_states if len(entered_states) > 1 else entered_states[0]
          return self.state_cls.separator.join(prefix)
  
      def _set_state(self, state_name):
          if isinstance(state_name, list):
              return [self._set_state(value) for value in state_name]
          else:
              a_state = self.get_state(state_name)
              return a_state.value if isinstance(a_state.value, Enum) else state_name
  
      def _trigger_event(self, _model, _trigger, _state_tree, *args, **kwargs):
          if _state_tree is None:
              _state_tree = self._build_state_tree(listify(getattr(_model, self.model_attribute)),
                                                   self.state_cls.separator)
          res = {}
          for key, value in _state_tree.items():
              if value:
                  with self(key):
                      tmp = self._trigger_event(_model, _trigger, value, *args, **kwargs)
                      if tmp is not None:
                          res[key] = tmp
              if res.get(key, False) is False and _trigger in self.events:
                  tmp = self.events[_trigger].trigger(_model, self, *args, **kwargs)
                  if tmp is not None:
                      res[key] = tmp
          return None if not res or all(v is None for v in res.values()) else any(res.values())
  