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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 add_highlight(self, artist, *args, **kwargs):
 """ Create, add, and return a highlighting artist. This method is should be called with an "unpacked" `Selection`, possibly with some fields set to None. It is up to the caller to register the artist with the proper `Selection` (by calling ``sel.extras.append`` on the result of this method) in order to ensure cleanup upon deselection. """

        hl = _pick_info.make_highlight(
            artist, *args,
            **ChainMap({"highlight_kwargs": self.highlight_kwargs}, kwargs))
        if hl:
            artist.axes.add_artist(hl)
            return hl