code: def _reflow_lines(parsed_tokens, indentation, max_line_length,
                    start_on_prefix_line):
      
  
      if unicode(parsed_tokens[0]) == 'def':
          # A function definition gets indented a bit more.
          continued_indent = indentation + ' ' * 2 * DEFAULT_INDENT_SIZE
      else:
          continued_indent = indentation + ' ' * DEFAULT_INDENT_SIZE
  
      break_after_open_bracket = not start_on_prefix_line
  
      lines = ReformattedLines(max_line_length)
      lines.add_indent(len(indentation.lstrip('\r\n')))
  
      if not start_on_prefix_line:
          # If splitting after the opening bracket will cause the first element
          # to be aligned weirdly, don't try it.
          first_token = get_item(parsed_tokens, 0)
          second_token = get_item(parsed_tokens, 1)
  
          if (
              first_token and second_token and
              unicode(second_token)[0] == '(' and
              len(indentation) + len(first_token) + 1 == len(continued_indent)
          ):
              return None
  
      for item in parsed_tokens:
          lines.add_space_if_needed(unicode(item), equal=True)
  
          save_continued_indent = continued_indent
          if start_on_prefix_line and isinstance(item, Container):
              start_on_prefix_line = False
              continued_indent = ' ' * (lines.current_size() + 1)
  
          item.reflow(lines, continued_indent, break_after_open_bracket)
          continued_indent = save_continued_indent
  
      return lines.emit()
docs: Reflow the lines so that it looks nice.