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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 process_prefix(self, prefix: str) -> Union[Namespace, None]: """ Add namespace to graph if it has a local match This allows qnames to be used without adding their respected namespaces if they are in the common_namespaces local dict. This is is to save a butt-ton of time trying to see what the ontology has as far as uris go. Args: prefix: prefix of the uri in the rdflib namespace to be checked if it exists in the local dict of common_namespaces. Returns: Namespace of uri if add or already exists; else None """

        if self.namespaces.get(prefix):
            return self.namespaces[prefix]
        iri: str = common_namespaces.get(prefix)
        if iri:
            return self.add_namespace(prefix, iri)