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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 _relative_name(self, record_name):
 """Returns sub-domain of a domain name"""

        # Handle None and empty strings as None
        if not record_name:
            return None
        subdomain = super(Provider, self)._relative_name(record_name)
        return subdomain if subdomain else None