If given node ' s ▁ left ' s right is pointing to given node and its right ' s ▁ left ▁ is ▁ pointing ▁ to ▁ the ▁ node ▁ ▁ itself ▁ then ▁ it ' s a leaf
return node -> left && node -> left -> right == node && node -> right && node -> right -> left == node ; }