function copy( x ) {
	var out;
	var len;
	var i;

	len = x.length;
	out = [];
	for ( i = 0; i < len; i++ ) {
		out.push( x[ i ] ); // use `Array#push` to ensure "fast" elements
	}
	return out;
}
Copies the elements of an indexed array-like object to a new "generic" array.

@param {Collection} x - input array
@returns {Array} output array

@example
var out = copy( [ 1, 2, 3 ] );
// returns [ 1, 2, 3 ]