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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_address_override(endpoint_type=PUBLIC):
 """Returns any address overrides that the user has defined based on the endpoint type. Note: this function allows for the service name to be inserted into the address if the user specifies {service_name}.somehost.org. :param endpoint_type: the type of endpoint to retrieve the override value for. :returns: any endpoint address or hostname that the user has overridden or None if an override is not present. """

    override_key = ADDRESS_MAP[endpoint_type]['override']
    addr_override = config(override_key)
    if not addr_override:
        return None
    else:
        return addr_override.format(service_name=service_name())