parameters: (self, user_str)
docstring: Lookup a function.
  
      Args:
        user_str: A raw string from the user, which may include uninterpreted
          arguments.  For example, 'pluralize person people' or 'test? admin'
  
      Returns:
        A 2-tuple of (function, args)
          function: Callable that formats data as a string
          args: Extra arguments to be passed to the function at expansion time
            Should be None to pass NO arguments, since it can pass a 0-tuple too.
docstring_summary: Lookup a function.
docstring_tokens: Lookup a function .
function: def Lookup(self, user_str):
      """Lookup a function.
  
      Args:
        user_str: A raw string from the user, which may include uninterpreted
          arguments.  For example, 'pluralize person people' or 'test? admin'
  
      Returns:
        A 2-tuple of (function, args)
          function: Callable that formats data as a string
          args: Extra arguments to be passed to the function at expansion time
            Should be None to pass NO arguments, since it can pass a 0-tuple too.
      """
      raise NotImplementedError
function_tokens: def Lookup ( self , user_str ) : raise NotImplementedError