code: def function_table(self, function_id=None):
          
          self._check_connected()
          function_table_keys = self.redis_client.keys(
              ray.gcs_utils.FUNCTION_PREFIX + "*")
          results = {}
          for key in function_table_keys:
              info = self.redis_client.hgetall(key)
              function_info_parsed = {
                  "DriverID": binary_to_hex(info[b"driver_id"]),
                  "Module": decode(info[b"module"]),
                  "Name": decode(info[b"name"])
              }
              results[binary_to_hex(info[b"function_id"])] = function_info_parsed
          return results
docs: Fetch and parse the function table.
  
          Returns:
              A dictionary that maps function IDs to information about the
                  function.