Why is there return in evalExpr function?

What would be the base case?

Prove that the algorithms printExpression and evalExpr print out and evaluate an arithmetic expression represented by a binary tree. Hint: Use induction and the recursive definition of a binary tree.

Evaluate Arithmetic Expressions o Specialization of a postorderAlgorithm evalExpr(v) traversal if v.isExternalO a recursive method returning return v.elementO the value of a subtree else when visiting an internal node, combine the values of the subtrees x evalExpr(v.leftO) yevalExpro.righo) operator stored at v return x y 5 1