sayHello() is using a Ternary Operator to check if person is defined.
If person is defined, it returns a greeting plus the persons name - "Hello, Laura!"
If the person is undefined, it returns "Hello, you!"
Can you shorten this function, using a default parameter?
To run the tests:
npm test default_parameters.test.js
Hint: make sure you're in the correct folder before running this command