code: def draw_heading(self, writer):
          
          if self.dirty == self.STATE_REFRESH:
              writer(u''.join(
                  (self.term.home, self.term.clear,
                   self.screen.msg_intro, '\n',
                   self.screen.header, '\n',)))
              return True
docs: Conditionally redraw screen when ``dirty`` attribute is valued REFRESH.
  
          When Pager attribute ``dirty`` is ``STATE_REFRESH``, cursor is moved
          to (0,0), screen is cleared, and heading is displayed.
  
          :param writer: callable writes to output stream, receiving unicode.
          :returns: True if class attribute ``dirty`` is ``STATE_REFRESH``.