def _legal_values(cmd, *args)
      raise ArgumentError, 'Invalid parameters' unless args[0].is_a?(Hash)

      @iface.call(cmd, args[0])
    end
def _legal_values(cmd, *args)
      raise ArgumentError, 'Invalid parameters' unless args[0].is_a?(Hash)

      @iface.call(cmd, args[0])
    end
def _fields