Write a function called solution takes in 2 parameters, a number and a function, and returns a function.

When the returned function is called, the input function will execute after input number milliseconds.

fun = solution(1800, () => {
  console.log('hello')
})
fun() // 'hello' will be printed out 1800ms after this function is called
fun() // 'hello' will be printed out 1800ms after this function is called