Implement a function functionLength(fn) that returns the number of parameters expected by a function.

The function should:

• Accept a single argument:
  • fn: A function
• Return the number of parameters the function expects (its length property)

Example

function sum(a, b, c) { return a + b + c; }
functionLength(sum); // 3

function greet(name) { return "Hello " + name; }
functionLength(greet); // 1

function noParams() { return 42; }
functionLength(noParams); // 0