Binary Search Tree (insert)

Instructions

Having binary node (data, left, right) we need to implement two methods binary search tree methods:

insert - accepts an argument data, then create an insert a new node at the appropriate location in the tree.
contains - accepts a data argument and return the true if node with given value already exists in the tree, otherwise returns false

Requirements that are always true for any given node in Binary Search Tree:

parent node value is always greater then value of the left node and less than value of the right node
left node value is always less then the value of parent node
right node value is always greater than parent node value

Example 1

val tree = Node(1)
tree.insert(4)
tree.insert(2)

// Result
//
//    1
//   / \
//  2   4

Example 2

val tree = Node(1)
tree.insert(4)
tree.insert(2)
tree.contains(4) // true
tree.contains(99) // false