class Redis::Cluster

def find_node_key(command)
  key = @command.extract_first_key(command)
  return if key.empty?
  slot = KeySlotConverter.convert(key)
  return unless @slot.exists?(slot)
  if @command.should_send_to_master?(command)
    @slot.find_node_key_of_master(slot)
  else
    @slot.find_node_key_of_slave(slot)
  end
end