docs: function (hashes, opts, cb) {
              if (isFunction(opts)) {
                  cb = opts;
                  opts = null;
              }
              opts = opts || {};
              hashes = hashes || [];
              var ret = new Promise();
              if (!hashes.length) {
                  ret.callback();
              } else {
                  var columns = Object.keys(hashes[0]);
                  ret = this["import"](columns, hashes.map(function (h) {
                      return columns.map(function (c) {
                          return h[c];
                      });
                  }), opts, cb);
              }
              return ret.classic(cb).promise();
          }