def list(self, pattern='*'):
    """Returns a list of groups that match the filters.

    Args:
      pattern: An optional pattern to filter the groups based on their display
          name. This can include Unix shell-style wildcards. E.g.
          ``"Production*"``.

    Returns:
      A list of Group objects that match the filters.
    """
    if self._group_dict is None:
      self._group_dict = collections.OrderedDict(
          (group.id, group) for group in self._client.list_groups())

    return [group for group in self._group_dict.values()
            if fnmatch.fnmatch(group.display_name, pattern)]
Returns a list of groups that match the filters.

    Args:
      pattern: An optional pattern to filter the groups based on their display
          name. This can include Unix shell-style wildcards. E.g.
          ``"Production*"``.

    Returns:
      A list of Group objects that match the filters.