code: def maybe_show_tree_param_default(show_tree, name, default):
      
      if show_tree:
          stream = show_tree if hasattr(show_tree, 'write') else sys.stdout
          stream.write('\n')
          stream.write('--' + name)
          stream.write('\n')
          stream.write(str(default))
          stream.write('\n')
          stream.write('--')
          stream.write('\n')
docs: Show a function parameter with default for an grammar-tree based on the show_tree flag
      (or file object), writing to the appropriate stream depending on the type
      of the flag.
  
      :param show_tree: Flag which determines whether the function parameter with
                        default is written to sys.stdout or not. (It is also to
                        pass a file like object, into which the ast will be
                        written).
      :param name:    The function parameter name.
      :param default: The function parameter default.