code: function (op) {
    return function(condition) {
      return this._compare(function(val) {
        var isNum = _.isNumber(val);
        switch (op) {
          case 'gt':
            return isNum && val > condition;
          case 'lt':
            return isNum && val < condition;
          case 'gte':
            return isNum && val >= condition;
          default:
            return isNum && val <= condition;
        }
      });
    };
  }
docs: ~_evalRelation
  
  Generic wrapper for evaluating lessThan, greaterThan, lessThanOrEqualTo, and greaterThanOrEqualTo
  
  @param {string} op - The operator, one of 'gt', 'lt', 'gte', and 'lte'
  @returns {function}