private ImTreeMapIntToObj KeepBalanced()
{
var delta = Left.Height - Right.Height;
return(delta >= 2 ? With(Left.Right.Height - Left.Left.Height == 1 ? Left.RotateLeft() : Left, Right).RotateRight()
: (delta <= -2 ? With(Left, Right.Left.Height - Right.Right.Height == 1 ? Right.RotateRight() : Right).RotateLeft()
: this));
}