Assign value to the context by key path

_define.js

/**
 * Assign value to the context by key path
 * @param {array} path ['foo', 'bar']
 * @param {mixed} value
 * @returns {*} result {foo:{bar: value}}
 */
function _define (path, value){
    return path.reduce((x, y, i) => {
        return x[y] = i === path.length - 1 && typeof value !== 'undefined' ? value : x[y] || {};
    }, this)
}