docs: def request_goto(self, tc=None):
          """
          Request a go to assignment.
  
          :param tc: Text cursor which contains the text that we must look for
                     its assignment. Can be None to go to the text that is under
                     the text cursor.
          :type tc: QtGui.QTextCursor
          """
          if not tc:
              tc = TextHelper(self.editor).word_under_cursor(
                  select_whole_word=True)
          if not self._definition or isinstance(self.sender(), QAction):
              self.select_word(tc)
          if self._definition is not None:
              QTimer.singleShot(100, self._goto_def)