code: def print_help(self, file=None):
          
          output = file or self.stderr
          CustomStderrOptionParser.print_help(self, output)
          output.write("\nCommands:\n")
          for command_def in self.command_definitions.values():
              command_def.opt_parser.print_help(output)
              output.write("\n")
docs: recursively call all command parsers' helps