function recurse( out, arr, depth ) {
	var v;
	var i;
	for ( i = 0; i < arr.length; i++ ) {
		v = arr[ i ];
		if ( depth && isArrayLikeObject( v ) ) {
			recurse( out, v, depth-1 );
		} else {
			out.push( v );
		}
	}
	return out;
}
Recursively flattens an array.

@private
@param {Array} out - output array
@param {ArrayLikeObject} arr - input array
@param {NonNegativeInteger} depth - recursion depth
@returns {Array} output array