code: def open_pager(self, data, wrap=None):
          
  
          pager = os.getenv('RTV_PAGER')
          if pager is None:
              pager = os.getenv('PAGER') or 'less'
          command = shlex.split(pager)
  
          if wrap:
              data_lines = content.Content.wrap_text(data, wrap)
              data = '\n'.join(data_lines)
  
          try:
              with self.suspend():
                  _logger.debug('Running command: %s', command)
                  p = subprocess.Popen(command, stdin=subprocess.PIPE)
                  try:
                      p.communicate(data.encode('utf-8'))
                  except KeyboardInterrupt:
                      p.terminate()
          except OSError as e:
              _logger.exception(e)
              self.show_notification('Could not open pager %s' % pager)
docs: View a long block of text using an external pager / viewer.  The setting
          of the RTV_PAGER variable will be used if set, otherwise the system's
          default pager is chosen, finally defaulting to 'less' if both RTV_PAGER
          and PAGER is unset in the calling environment.
  
          The data string will be piped directly to the pager.