code: function key(obj, vonly) {
    var buffer = new Buffer(0)
      , item;
    if(obj.expiry !== undefined && !vonly) {
      buffer = this.expiry(obj.expiry);
    }
    item = this[obj.rtype](obj, vonly);
    return Buffer.concat(
      [
        buffer,
        item
      ],
      buffer.length + item.length
    )
  }
docs: Get the buffer for a key.
  
  @param obj The object representing the key and value.
  @param vonly A boolean that forces only the value to be encoded.