docs: def aname(cls, map_name, attached_name, parent_name=None):
          """
          Generates a container name that should be used for creating new attached volume containers and checking the
          status of existing containers.
  
          In this implementation, the format will be ``<map name>.<attached>``, or ``<map name>.<parent name>.<attached>``
          if the parent container configuration name is provided.
  
          :param map_name: Container map name.
          :type map_name: unicode | str
          :param attached_name: Attached container alias.
          :type attached_name: unicode | str
          :param parent_name: Container configuration name that has contains attached container.
          :type parent_name: unicode | str
          :return: Container name.
          :rtype: unicode | str
          """
          if parent_name:
              return '{0}.{1}.{2}'.format(map_name, parent_name, attached_name)
          return '{0}.{1}'.format(map_name, attached_name)