Recall from lecture that a binary tree T is either: 1. null (the empty tree); or 2. a root noder with two subtrees T and Tg, both of which are binary trees. Consider the following algorithm nunLeaves (T) that takes as input a binary tree T and returns the number of leaves in the tree. Prove by structural induction that for every binary tree T, numLeaves(T) returns the number of leaves of T.

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