let x = 10;
let b = 30 + 1;
b = b + 5;
x + b // evaluates to JSNumber { value: 46 }

let x = "Hello World"
x //  evaluates to JSString  { value: "Hello World" }

// its own scope
{
  let x = 1;
}

function x(a, b) { 
  return a + b;
}

x(2, 3); // evaluates to 5

let obj = {a: 3, b: "Hello World"}; // evaluates to JSObject { value: HashMap /w "a" - 3 as JSNumber and "b" - "Hello World" as JSString }