fix documentation of reduce

Author: make-github-pseudonymous-again

src/reduce/_reduce.js

@@ -1,10 +1,18 @@
 /**
- * Applies the accumulator function iteratively on the
- * last return value of the accumulator and the next
- * value in the iterable. The initial value is the initializer
- * parameter.
+ * Applies the accumulator function iteratively on the last return value of the
+ * accumulator and the next value in the input iterable. The initial value is
+ * the initializer parameter.
+ *
+ * @example
+ * _reduce( ( x , y ) => x + y , range( 10 ) , 0 ) ; // returns 45
+ *
+ * @example
+ * _reduce( ( x , y ) => x + y , range( 10 ) , 100 ) ; // returns 145
+ *
+ * @param {Iterable} iterable - The input iterable.
+ * @param {Object} initializer - The initial value of the reduction.
+ * @returns {Object} - The reduction of the elements of <code>iterable</code>.
  */
-
 export function _reduce ( accumulator , iterable , initializer ) {
 
 	for ( let item of iterable ) {

src/reduce/reduce.js

@@ -2,10 +2,20 @@ import { _reduce } from './_reduce' ;
 import { iter } from '../base/iter' ;
 
 /**
- * Applies the accumulator function iteratively on the
- * last return value of the accumulator and the next
- * value in the iterable. The initial value is the initializer
- * parameter.
+ * Applies the accumulator function iteratively on the last return value of the
+ * accumulator and the next value in the input iterable. The initial value is
+ * the initializer parameter. If no initial value is given, the first element
+ * of the input iterable is used.
+ *
+ * @example
+ * _reduce( ( x , y ) => x + y , range( 10 ) , 0 ) ; // returns 45
+ *
+ * @example
+ * _reduce( ( x , y ) => x + y , range( 10 ) , 100 ) ; // returns 145
+ *
+ * @param {Iterable} iterable - The input iterable.
+ * @param {Object} initializer - The initial value of the reduction.
+ * @returns {Object} - The reduction of the elements of <code>iterable</code>.
  */
 
 export function reduce ( accumulator , iterable , initializer = undefined ) {