Update the internal state of the Plot to represent the given
        key tuple (where integers represent frames). Returns this
        state.

def update_frame(self, key, ranges=None):
        """
        Update the internal state of the Plot to represent the given
        key tuple (where integers represent frames). Returns this
        state.
        """
        ranges = self.compute_ranges(self.layout, key, ranges)
        for r, c in self.coords:
            subplot = self.subplots.get((r, c), None)
            if subplot is not None:
                subplot.update_frame(key, ranges)
        title = self._get_title_div(key)
        if title:
            self.handles['title'] = title