Write proper C++ for a function called check Invarlant that returns true if an input binary tree satisfies the invariant of an unbalanced bin search tree, and false if there is a violation of the binary search tree invariant. The function should receive a single argument, bt node" t Document your code, and specifically state what the invariant is (in English) that the code is checking. Write proper C++ for a function called check Invarlant that returns true if an input binary tree satisfies the invariant of an unbalanced bin search tree, and false if there is a violation of the binary search tree invariant. The function should receive a single argument, bt node" t Document your code, and specifically state what the invariant is (in English) that the code is checking