Array.prefixEach preppends string to every element in array

array.prefixEach.js

/**
 * Prefixes each array element with given
 * @param {String} prefix
 * @usage e.g var pfixed = ["one", "two", "three"].prefixEach("number: ");
 */
Array.prototype.prefixEach = function(prefix) {
    return this.map(_ary(String.prototype.concat.bind(prefix)));
};

function _ary(fn, arity) {
    arity = arity || 1;
    return function() {
        var args = Array.prototype.slice.call(arguments, 0, arity);
        return fn.apply(null, args);
    };
}