code: function (operand) {                                                              // 624
        if (typeof operand === 'string') {                                                                      // 625
          // Don't ask me why, but by experimentation, this seems to be what Mongo                              // 626
          // does.                                                                                              // 627
          operand = 0;                                                                                          // 628
        } else if (typeof operand !== 'number') {                                                               // 629
          throw Error("$size needs a number");                                                                  // 630
        }                                                                                                       // 631
        return function (value) {                                                                               // 632
          return isArray(value) && value.length === operand;                                                    // 633
        };                                                                                                      // 634
      }
docs: 623