SOURCE

function assert(value, text) {
  if(value === true) {
    console.log(text)
  } else {
    console.log('error')
  }
}

// assert(typeof fun === "function", "fun is a function even though its definition isn'n reached yet")

// assert(typeof myFunExp === "undefined","but we can not  access function expression")

// function fun() {
  
// }
// var myFunExp = () => {}

// 函数重载
assert(typeof fun === "function", "we access the function")

var fun = 3

assert(typeof fun === "number", "now we access the number")

function fun() {
  
}

assert(typeof fun === "number","still a number")