code: def read_next_line(self):
          
  
          next_line = self.file.readline()
  
          if not next_line or next_line[-1:] != '\n':
              # no newline on last line of file
              self.file = None
          else:
              # trim newline characters
              next_line = next_line[:-1]
  
          expanded = next_line.expandtabs()
  
          edit = urwid.Edit("", expanded, allow_tab=True)
          edit.set_edit_pos(0)
          edit.original_text = next_line
          self.lines.append(edit)
  
          return next_line
docs: Read another line from the file.