Please give your answer in OCaml

Suppose we define the binary tree data type as follows: \( \begin{array}{l} \text { type 'a binary_tree }= \\ \text { | Empty } \\ \text { | Node of 'a } * \text { 'a binary_tree * 'a binary_tree; } ;\end{array} \) a) Write a function called num_of_leaves to count the number of leaves in a binary tree. b) Write a function called get_all_leaves to collect all the leaves in a list