function getArrayLike( arr, idx ) {
	return arr.get( idx );
}
Returns an element from an array-like object supporting the get/set protocol.

@private
@param {Collection} arr - input array
@param {NonNegativeInteger} idx - element index
@returns {*} element value

@example
var arr = [ 1, 2, 3, 4 ];

function get( idx ) {
   return arr[ idx ];
}

function set( value, idx ) {
   arr[ idx ] = value;
}

arr.get = get;
arr.set = set;

var v = getArrayLike( arr, 2 );
// returns 3