Returns either a value or the word "ERROR"
Returns a value if it is called with a list that contains:
A single number, or`
An "ADD" ("+") command or "MULTIPLY" ("*") command in infix notation where the two operands must be recursively evaluated by MyEval.
My question is how do you take an expression that looks like: (1 + 2) and turn it into (+ 1 2) in the code?