function contains( arr, v ) {
	var len;
	var i;

	len = arr.length;
	for ( i = 0; i < len; i++ ) {
		if ( arr[ i ] === v ) {
			return true;
		}
	}
	return false;
}
Tests whether an array contains a provided value.

@private
@param {Array} arr - input array
@param {*} v - test value
@returns {boolean} boolean indicating whether an array contains a provided value

@example
var bool = contains( [ 1, 2, 3 ], 1 );
// returns true

bool = contains( [ 1, 2, 3 ], 4 );
// returns false