parameters: (self, line, font_attr_segs=None)
docstring: Append a single line of text.
  
      Args:
        line: (str) The text to be added to the end.
        font_attr_segs: (list of tuples) Font attribute segments of the appended
          line.
docstring_summary: Append a single line of text.
docstring_tokens: Append a single line of text .
function: def append(self, line, font_attr_segs=None):
      """Append a single line of text.
  
      Args:
        line: (str) The text to be added to the end.
        font_attr_segs: (list of tuples) Font attribute segments of the appended
          line.
      """
  
      self._lines.append(line)
      if font_attr_segs:
        self._font_attr_segs[len(self._lines) - 1] = font_attr_segs
function_tokens: def append ( self , line , font_attr_segs = None ) : self . _lines . append ( line ) if font_attr_segs : self . _font_attr_segs [ len ( self . _lines ) - 1 ] = font_attr_segs