<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _updateWordSet(self):
 """Make a set of words, which shall be completed, from text """

        self._wordSet = set(self._keywords) | set(self._customCompletions)

        start = time.time()

        for line in self._qpart.lines:
            for match in _wordRegExp.findall(line):
                self._wordSet.add(match)
            if time.time() - start > self._WORD_SET_UPDATE_MAX_TIME_SEC:
                """It is better to have incomplete word set, than to freeze the GUI"""
                break