function arraySum(array, iteratee) {
	      var length = array.length,
	          result = 0;

	      while (length--) {
	        result += +iteratee(array[length]) || 0;
	      }
	      return result;
	    }
A specialized version of `_.sum` for arrays without support for callback
shorthands and `this` binding..

@private
@param {Array} array The array to iterate over.
@param {Function} iteratee The function invoked per iteration.
@returns {number} Returns the sum.