Answer Happy

Implement a function that does the following: Given a binarysearch tree, return the smallest node, then move the pointer to thenext smallest node in the tree. Upon calling the function anothertime, it should return the next smallest node and so on, when thereare no more nodes left, it should return NULL.
Important note: Should notinitialise any variables in the main function.
Some helper function and their definitions have beenprovided below