const React = /* Implement this */
  
  function HelloComponent(){
    const [myNumber, setMyNumber] = React.useState(0);
    // Simulate rendering data to a screen
    console.log("My number:", myNumber);
    // Simulate rendering a clickable button
    const click = ()=> setMyNumber((num)=> num + 1);
    return click; 
  }
  
  React.mount(HelloComponent); // prints 0
  React.simulateClick(HelloComponent); // prints 1
  React.simulateClick(HelloComponent); // prints 2
  React.simulateClick(HelloComponent); // prints 3

I am working through this exercise now, but I'm already finding myself doing some pretty hacky things to make this work (like finding out who called a function using arguments.callee.caller.name). Still, it's pretty interesting.

Edit: My solution to this: https://gist.github.com/rashkov/f765917d09ebd629f385c21195f4...