code: def get_curie_prefix(self, uri):
          ''' Return the CURIE's prefix:'''
          for key, value in self.uri_map.items():
              if uri.startswith(key):
                  return value
          return Nonf get_curie_prefix(self, uri):
          ''' Return the CURIE's prefix:'''
          for key, value in self.uri_map.items():
              if uri.startswith(key):
                  return value
          return None
docs: Return the CURIE's prefix: