(function(define) {'use strict';
define(function(require) {

return function(Base) {

   var Variable, Dataset, utils;

   Variable = Base.Variable;
   Dataset  = Base.Dataset;
   utils    = require('./utils');

   /**
    * Return the sum of the values.
    * `skipMissing` defaults to false.  If `skipMissing` is false and
    * `this` has missing values, result is NaN.
    */
   Variable.prototype.sum = function sum(skipMissing) {
      return this.reduce(utils.op.add, 0, skipMissing);
   };

   return Base;
};

});

}(typeof define === 'function' && define.amd ? define : function(factory) {
   'use strict';
   module.exports = factory(require);
}));

(function(define) {'use strict';
define(function(require) {

return function(Base) {
   /* eslint-disable no-unused-vars */
   var Variable, Dataset, utils;
   /* eslint-enable */

   Variable = Base.Variable;
   Dataset  = Base.Dataset;
   utils    = require('./utils');

   /**
    * Return the sum of the values.
    * `skipMissing` defaults to false.  If `skipMissing` is false and
    * `this` has missing values, result is NaN.
    */
   Variable.prototype.sum = function sum(skipMissing) {
      return this.reduce(utils.op.add, 0, skipMissing);
   };

   return Base;
};

});

}(typeof define === 'function' && define.amd ? define : function(factory) {
   'use strict';
   module.exports = factory(require);
}));

Make eslint happy, temporarily.