Problem Statement

A function is a body of code that returns a value. The value returned may depend on arguments provided to the function.

Write a definition of a function called "multiply" that takes two arguments and returns their product. (Argument types should be chosen so as not to distract from showing how functions are created and values returned).

Let's start with the solution:

def (multiply a b)
  a*b

(multiply 3 4)
=> 12

(multiply 3 :a 4)  # arg order doesn't matter here, but try subtract instead
=> 12

def (multiply a b|by)
  (* a b)

multiply 3 :by 4
=> 12