code: def contains(self, index: Union[SchemaKey, int, str]) -> bool:
          
  
          LOGGER.debug('SchemaCache.contains >>> index: %s', index)
  
          rv = None
          if isinstance(index, SchemaKey):
              rv = (index in self._schema_key2schema)
          elif isinstance(index, int) or (isinstance(index, str) and ':2:' not in index):
              rv = (int(index) in self._seq_no2schema_key)
          elif isinstance(index, str):
              rv = (schema_key(index) in self._schema_key2schema)
          else:
              rv = False
  
          LOGGER.debug('SchemaCache.contains <<< %s', rv)
          return rv
docs: Return whether the cache contains a schema for the input key, sequence number, or schema identifier.
  
          :param index: schema key, sequence number, or sequence identifier
          :return: whether the cache contains a schema for the input index