docs: def create_graph_name(suffix='', dirname=None):
      """Create a graph name using the name of the caller.
  
      :param suffix: optional suffix to add to name
      :param dirname: optional directory name
  
      :return: path for the named graph
      :rtype: string
  
      """
      if suffix:
          suffix = '-%s' % suffix
      caller = get_callers_name(level=3)
      name = '%s%s%s%s' % (__prefix, caller, suffix, __suffix)
      if dirname:
          name = os.path.join(dirname, name)
      return name