text: """
  Contexts are the "values" that Python would return. However Contexts are at the
  same time also the "contexts" that a user is currently sitting in.
  
  A ContextSet is typically used to specify the return of a function or any other
  static analysis operation. In jedi there are always multiple returns and not
  just one.
  """
  from parso.python.tree import ExprStmt, CompFor
  
  from jedi import debug
  from jedi._compatibility import Python3Method, zip_longest, unicode
  from jedi.parser_utils import clean_scope_docstring, get_doc_with_call_signature
  from jedi.common import BaseContextSet, BaseContext
  from jedi.evaluate.helpers import EvaluatorIndexError, EvaluatorTypeError, \
      EvaluatorKeyError
  
  
  class Context(BaseContext):
      """
      Should be defined, otherwise the API returns empty types.
      """
  
      predefined_names = {}
      tree_node = None
      """
      To be defined by subclasses.
      """
  
      @property
      def api_type(self):
          # By default just lower name of the class. Can and should be
          # overwritten.
          return self.__class__.__name__.lower()
  
      @debug.increase_indent
      def execute(self, arguments):
          """
          In contrast to py__call__ this function is always available.
  
          `hasattr(x, py__call__)` can also be checked to see if a context is
          executable.
          """
          if self.evaluator.is_analysis:
              arguments.eval_all()
  
          debug.dbg('execute: %s %s', self, arguments)
          from jedi.evaluate import stdlib
          try:
              # Some stdlib functions like super(), namedtuple(), etc. have been
              # hard-coded in Jedi to support them.
              return stdlib.execute(self.evaluator, self, arguments)
          except stdlib.NotInStdLib:
              pass
  
          try:
              func = self.py__call__
          except AttributeError:
              debug.warning("no execution possible %s", self)
              return NO_CONTEXTS
          else:
              context_set = func(arguments)
              debug.dbg('execute result: %s in %s', context_set, self)
              return context_set
  
          return self.evaluator.execute(self, arguments)
  
      def execute_evaluated(self, *value_list):
          """
          Execute a function with already executed arguments.
          """
          from jedi.evaluate.arguments import ValuesArguments
          arguments = ValuesArguments([ContextSet(value) for value in value_list])
          return self.execute(arguments)
  
      def iterate(self, contextualized_node=None, is_async=False):
          debug.dbg('iterate %s', self)
          try:
              if is_async:
                  iter_method = self.py__aiter__
              else:
                  iter_method = self.py__iter__
          except AttributeError:
              if contextualized_node is not None:
                  from jedi.evaluate import analysis
                  analysis.add(
                      contextualized_node.context,
                      'type-error-not-iterable',
                      contextualized_node.node,
                      message="TypeError: '%s' object is not iterable" % self)
              return iter([])
          else:
              return iter_method()
  
      def get_item(self, index_contexts, contextualized_node):
          from jedi.evaluate.compiled import CompiledObject
          from jedi.evaluate.context.iterable import Slice, Sequence
          result = ContextSet()
  
          for index in index_contexts:
              if isinstance(index, Slice):
                  index = index.obj
              if isinstance(index, CompiledObject):
                  try:
                      index = index.get_safe_value()
                  except ValueError:
                      pass
  
              if type(index) not in (float, int, str, unicode, slice, bytes):
                  # If the index is not clearly defined, we have to get all the
                  # possiblities.
                  if isinstance(self, Sequence) and self.array_type == 'dict':
                      result |= self.dict_values()
                  else:
                      result |= iterate_contexts(ContextSet(self))
                  continue
  
              # The actual getitem call.
              try:
                  getitem = self.py__getitem__
              except AttributeError:
                  from jedi.evaluate import analysis
                  # TODO this context is probably not right.
                  analysis.add(
                      contextualized_node.context,
                      'type-error-not-subscriptable',
                      contextualized_node.node,
                      message="TypeError: '%s' object is not subscriptable" % self
                  )
              else:
                  try:
                      result |= getitem(index)
                  except EvaluatorIndexError:
                      result |= iterate_contexts(ContextSet(self))
                  except EvaluatorKeyError:
                      # Must be a dict. Lists don't raise KeyErrors.
                      result |= self.dict_values()
                  except EvaluatorTypeError:
                      # The type is wrong and therefore it makes no sense to do
                      # anything anymore.
                      result = NO_CONTEXTS
          return result
  
      def eval_node(self, node):
          return self.evaluator.eval_element(self, node)
  
      @Python3Method
      def py__getattribute__(self, name_or_str, name_context=None, position=None,
                             search_global=False, is_goto=False,
                             analysis_errors=True):
          """
          :param position: Position of the last statement -> tuple of line, column
          """
          if name_context is None:
              name_context = self
          from jedi.evaluate import finder
          f = finder.NameFinder(self.evaluator, self, name_context, name_or_str,
                                position, analysis_errors=analysis_errors)
          filters = f.get_filters(search_global)
          if is_goto:
              return f.filter_name(filters)
          return f.find(filters, attribute_lookup=not search_global)
  
      def create_context(self, node, node_is_context=False, node_is_object=False):
          return self.evaluator.create_context(self, node, node_is_context, node_is_object)
  
      def is_class(self):
          return False
  
      def py__bool__(self):
          """
          Since Wrapper is a super class for classes, functions and modules,
          the return value will always be true.
          """
          return True
  
      def py__doc__(self, include_call_signature=False):
          try:
              self.tree_node.get_doc_node
          except AttributeError:
              return ''
          else:
              if include_call_signature:
                  return get_doc_with_call_signature(self.tree_node)
              else:
                  return clean_scope_docstring(self.tree_node)
          return None
  
  
  def iterate_contexts(contexts, contextualized_node=None, is_async=False):
      """
      Calls `iterate`, on all contexts but ignores the ordering and just returns
      all contexts that the iterate functions yield.
      """
      return ContextSet.from_sets(
          lazy_context.infer()
          for lazy_context in contexts.iterate(contextualized_node, is_async=is_async)
      )
  
  
  class TreeContext(Context):
      def __init__(self, evaluator, parent_context, tree_node):
          super(TreeContext, self).__init__(evaluator, parent_context)
          self.predefined_names = {}
          self.tree_node = tree_node
  
      def __repr__(self):
          return '<%s: %s>' % (self.__class__.__name__, self.tree_node)
  
  
  class ContextualizedNode(object):
      def __init__(self, context, node):
          self.context = context
          self.node = node
  
      def get_root_context(self):
          return self.context.get_root_context()
  
      def infer(self):
          return self.context.eval_node(self.node)
  
  
  class ContextualizedName(ContextualizedNode):
      # TODO merge with TreeNameDefinition?!
      @property
      def name(self):
          return self.node
  
      def assignment_indexes(self):
          """
          Returns an array of tuple(int, node) of the indexes that are used in
          tuple assignments.
  
          For example if the name is ``y`` in the following code::
  
              x, (y, z) = 2, ''
  
          would result in ``[(1, xyz_node), (0, yz_node)]``.
          """
          indexes = []
          node = self.node.parent
          compare = self.node
          while node is not None:
              if node.type in ('testlist', 'testlist_comp', 'testlist_star_expr', 'exprlist'):
                  for i, child in enumerate(node.children):
                      if child == compare:
                          indexes.insert(0, (int(i / 2), node))
                          break
                  else:
                      raise LookupError("Couldn't find the assignment.")
              elif isinstance(node, (ExprStmt, CompFor)):
                  break
  
              compare = node
              node = node.parent
          return indexes
  
  
  class ContextSet(BaseContextSet):
      def py__class__(self):
          return ContextSet.from_iterable(c.py__class__() for c in self._set)
  
      def iterate(self, contextualized_node=None, is_async=False):
          from jedi.evaluate.lazy_context import get_merged_lazy_context
          type_iters = [c.iterate(contextualized_node, is_async=is_async) for c in self._set]
          for lazy_contexts in zip_longest(*type_iters):
              yield get_merged_lazy_context(
                  [l for l in lazy_contexts if l is not None]
              )
  
  
  NO_CONTEXTS = ContextSet()
  
  
  def iterator_to_context_set(func):
      def wrapper(*args, **kwargs):
          return ContextSet.from_iterable(func(*args, **kwargs))
  
      return wrapper
  