def request_goto(self, tc=None):
if not tc:<EOL><INDENT>tc = TextHelper(self.editor).word_under_cursor(<EOL>select_whole_word=True)<EOL><DEDENT>if not self._definition or isinstance(self.sender(), QAction):<EOL><INDENT>self.select_word(tc)<EOL><DEDENT>if self._definition is not None:<EOL><INDENT>QTimer.singleShot(<NUM_LIT:100>, self._goto_def)<EOL><DEDENT>
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