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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 auth_scheme(self):
 """ If an Authorization header is present get the scheme It is expected to be the first string in a space separated list & will always be returned lowercase. :return: str or None """


        try:
            auth = getattr(self, 'auth')
            return naked(auth.split(' ')[0]).lower()
        except (AttributeError, IndexError):
            return None