class_docstr: Create a new Group that contains common members. All
  defined groups are stored in ``Group.groups``. Group
  names must be unique.
  
  Parameters
  ----------
  name : str
      Group name.
  space : alphapy.Space, optional
      Namespace for the given group.
  dynamic : bool, optional, default ``True``
      Flag for defining whether or not the group membership
      can change.
  members : set, optional
      The initial members of the group, especially if the
      new group is fixed, e.g., not ``dynamic``.
  
  Attributes
  ----------
  groups : dict
      Class variable for storing all known groups
  
  Examples
  --------
  
  >>> Group('tech')
code: def __init__(self, name, space=Space(), dynamic=True, members=set()):
      # code
      if not name in Group.groups:
          self.name = name
          self.space = space
          self.dynamic = dynamic
          self.members = members
          # add group to groups list
          Group.groups[name] = self
      else:
          logger.info("Group already %s exists", name)
  
file_path: AlphaPy/alphapy/group.py
imports: from alphapy.globals import USEP
  from alphapy.space import Space
  import logging
label_desc: Use image node_id 1 to create a new Group object from inherited base classes: object with example: obj = Group(name, space, dynamic, members)