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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _push(self, context=0):
 """Add a new token stack, context, and textbuffer to the list."""

        new_ident = (self._head, context)
        if new_ident in self._bad_routes:
            raise BadRoute(context)

        self._stacks.append([[], context, [], new_ident])
        self._depth += 1