def update(self, edge=None):
        if self._root is None: return
        # If the edge isn't a parse edge, do nothing.
        if edge is not None:
            if edge.lhs() != self._grammar.start(): return
            if edge.span() != (0, self._chart.num_leaves()): return

        for parse in self._chart.parses(self._grammar.start()):
            if self._trees not in parse:
                self._add(parse)
dataset/ETHPy150Open nltk/nltk/nltk/app/chartparser_app.py/ChartResultsView.update/swapped operands of `not in`