code: function(k) {
          var ctx = u.context(SMALL);
          logger.debugf('Invoke containsKey(msgId=%d,key=%s)', ctx.id, u.str(k));
          return futureKey(ctx, 0x0F, k, p.encodeKey(k), p.complete(p.hasSuccess));
        }
docs: Check whether the given key is present.
  
  @param k {(String|Object)} Key to check for presence.
  @returns {module:promise.Promise.<boolean>}
  A promise that will be completed with true if there is a value
  associated with the key, or false otherwise.
  @memberof Client#
  @since 0.3