code: def add_namespace(self, prefix: str, uri: str) -> Namespace:
          
          ns = Namespace(uri)
          if not self.namespaces.get(prefix):
              self.namespaces[prefix] = ns
              self.g.bind(prefix, uri)
          return ns
docs: Adds a prefix to uri mapping (namespace)
  
          Adds a namespace to replace any uris in iris with shortened prefixes
          in order to make the file more readable. Not techniqually necessary.
  
          Args:
              prefix: prefix that will substitute the uri in the iri
              uri: the uri in the iri to be substituted by the prefix
  
          Returns:
              A namespace of the uri
  
          Example:
              add_namespace(
                  prefix = "rdfs",
                  uri = 'http://www.w3.org/2000/01/rdf-schema#',
              )
              makes
              "http://www.w3.org/2000/01/rdf-schema#label 'neuron'@en ;",
              become
              "rdfs:label 'neuron'@en ;"