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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 save_lyrics(self, extension='json', overwrite=False, verbose=True, binary_encoding=False):
 """Allows user to save all lyrics within an Artist object"""

        extension = extension.lstrip(".")
        assert (extension == 'json') or (extension == 'txt'), "format_ must be JSON or TXT"

        for song in self.songs:
            song.save_lyrics(extension=extension, overwrite=overwrite, verbose=verbose, binary_encoding=binary_encoding)