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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 get_newest_commit_date(self):
        '''
        Get datetime of newest commit involving this file

        :returns: Datetime of newest commit
        '''
        newest_commit = self.get_newest_commit()
        return self.git.get_commit_date(newest_commit, self.tz_name)