Delete a Tree

#include<stdio.h>
struct binarysearchtree
{
      int data;
      struct binarysearchtree* left;
      struct binarysearchtree* right;
};
typedef struct binarysearchtree* tree;

void tree_free(tree T)
{
  if (T==NULL)
     return;
  else
  {
      tree_free(T->left);
      tree_free(T->right);
      free(T);
  }
}