code: def _help_preprocess(self, help, cmdname):
          
          preprocessors = {
              "${name}": self._help_preprocess_name,
              "${option_list}": self._help_preprocess_option_list,
              "${command_list}": self._help_preprocess_command_list,
              "${help_list}": self._help_preprocess_help_list,
              "${cmd_name}": self._help_preprocess_cmd_name,
              "${cmd_usage}": self._help_preprocess_cmd_usage,
              "${cmd_option_list}": self._help_preprocess_cmd_option_list,
          }
  
          for marker, preprocessor in preprocessors.items():
              if marker in help:
                  help = preprocessor(help, cmdname)
          return help
docs: Hook to preprocess a help string before writing to stdout.
  
              "help" is the help string to process.
              "cmdname" is the canonical sub-command name for which help
                  is being given, or None if the help is not specific to a
                  command.
  
          By default the following template variables are interpolated in
          help content. (Note: these are similar to Python 2.4's
          string.Template interpolation but not quite.)
  
          ${name}
              The tool's/shell's name, i.e. 'self.name'.
          ${option_list}
              A formatted table of options for this shell/tool.
          ${command_list}
              A formatted table of available sub-commands.
          ${help_list}
              A formatted table of additional help topics (i.e. 'help_*'
              methods with no matching 'do_*' method).
          ${cmd_name}
              The name (and aliases) for this sub-command formatted as:
              "NAME (ALIAS1, ALIAS2, ...)".
          ${cmd_usage}
              A formatted usage block inferred from the command function
              signature.
          ${cmd_option_list}
              A formatted table of options for this sub-command. (This is
              only available for commands using the optparse integration,
              i.e.  using @cmdln.option decorators or manually setting the
              'optparser' attribute on the 'do_*' method.)
  
          Returns the processed help.