def insert(self, edge, *child_pointer_lists):
        # Is it a new edge?
        if edge not in self._edge_to_cpls:
            # Add it to the list of edges.
            self._append_edge(edge)
            # Register with indexes.
            self._register_with_indexes(edge)

        # Get the set of child pointer lists for this edge.
        cpls = self._edge_to_cpls.setdefault(edge, OrderedDict())
        chart_was_modified = False
        for child_pointer_list in child_pointer_lists:
            child_pointer_list = tuple(child_pointer_list)
            if child_pointer_list not in cpls:
                # It's a new CPL; register it, and return true.
                cpls[child_pointer_list] = True
                chart_was_modified = True
        return chart_was_modified
Add a new edge to the chart, and return True if this operation
dataset/ETHPy150Open nltk/nltk/nltk/parse/chart.py/Chart.insert