text: /**
  * @license Apache-2.0
  *
  * Copyright (c) 2019 The Stdlib Authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *    http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
  
  'use strict';
  
  // MODULES //
  
  var setReadOnly = require( '@stdlib/utils/define-nonenumerable-read-only-property' );
  var isIteratorLike = require( '@stdlib/assert/is-iterator-like' );
  var isFunction = require( '@stdlib/assert/is-function' );
  var iteratorSymbol = require( '@stdlib/symbol/iterator' );
  var incrsum = require( './../../../incr/sum' );
  
  
  // MAIN //
  
  /**
  * Returns an iterator which iteratively computes a cumulative sum.
  *
  * @param {Iterator} iterator - input iterator
  * @throws {TypeError} must provide an iterator
  * @returns {Iterator} iterator
  *
  * @example
  * var runif = require( '@stdlib/random/iter/uniform' );
  *
  * var rand = runif( -10.0, 10.0, {
  *     'iter': 100
  * });
  *
  * var it = itercusum( rand );
  *
  * var v = it.next().value;
  * // returns <number>
  *
  * v = it.next().value;
  * // returns <number>
  *
  * v = it.next().value;
  * // returns <number>
  *
  * // ...
  */
  function itercusum( iterator ) {
  	var iter;
  	var FLG;
  	var acc;
  	if ( !isIteratorLike( iterator ) ) {
  		throw new TypeError( 'invalid argument. Must provide an iterator. Value: `' + iterator + '`.' );
  	}
  	acc = incrsum();
  
  	// Create an iterator protocol-compliant object:
  	iter = {};
  	setReadOnly( iter, 'next', next );
  	setReadOnly( iter, 'return', end );
  
  	// If an environment supports `Symbol.iterator`, make the iterator iterable:
  	if ( iteratorSymbol && isFunction( iterator[ iteratorSymbol ] ) ) {
  		setReadOnly( iter, iteratorSymbol, factory );
  	}
  	return iter;
  
  	/**
  	* Returns an iterator protocol-compliant object containing the next iterated value.
  	*
  	* @private
  	* @returns {Object} iterator protocol-compliant object
  	*/
  	function next() {
  		var v;
  		if ( FLG ) {
  			return {
  				'done': true
  			};
  		}
  		v = iterator.next();
  		if ( v.done ) {
  			FLG = true;
  			return v;
  		}
  		if ( typeof v.value === 'number' ) {
  			v = acc( v.value );
  		} else {
  			v = acc( NaN );
  		}
  		return {
  			'value': v,
  			'done': false
  		};
  	}
  
  	/**
  	* Finishes an iterator.
  	*
  	* @private
  	* @param {*} [value] - value to return
  	* @returns {Object} iterator protocol-compliant object
  	*/
  	function end( value ) {
  		FLG = true;
  		if ( arguments.length ) {
  			return {
  				'value': value,
  				'done': true
  			};
  		}
  		return {
  			'done': true
  		};
  	}
  
  	/**
  	* Returns a new iterator.
  	*
  	* @private
  	* @returns {Iterator} iterator
  	*/
  	function factory() {
  		return itercusum( iterator[ iteratorSymbol ]() );
  	}
  }
  
  
  // EXPORTS //
  
  module.exports = itercusum;
  