code: def find_prefix(self, iri: Union[URIRef, Literal, str]) -> Union[None, str]:
          
          iri = str(iri)
          max_iri_len = 0
          max_prefix = None
          for prefix, uri in common_namespaces.items():
              if uri in iri and max_iri_len < len(uri): # if matched uri is larger; replace as king
                  max_prefix = prefix
                  max_iri_len = len(uri)
          return max_prefix
docs: Finds if uri is in common_namespaces
  
          Auto adds prefix if incoming iri has a uri in common_namespaces. If its not in the local
          library, then it will just be spit out as the iri and not saved/condensed into qualified
          names.
  
          The reason for the maxes is find the longest string match. This is to avoid accidently
          matching iris with small uris when really is a more complete uri that is the match.
  
          Args: iri: iri to be searched to find a known uri in it.
  
          Eample:
              In  [1]: print(find_prefix("http://www.w3.org/2000/01/rdf-schema#label"))
              Out [1]: "http://www.w3.org/2000/01/rdf-schema#"
              In  [2]: print(find_prefix("http://made_up_uri/label"))
              Out [2]: None