docs: function(k, opts) {
          var ctx = u.context(SMALL);
          logger.debugl(function() {return ['Invoke remove(msgId=%d,key=%s,opts=%s)',
                                            ctx.id, u.str(k), JSON.stringify(opts)]; });
          var decoder = p.decodePrevOrElse(opts, p.hasSuccess, p.complete(p.hasSuccess));
          return futureKey(ctx, 0x0B, k, p.encodeKey(k), decoder, opts);
        }