function setup() {

  createCanvas(400, 400);

}

​

// this function is declared by the user

function smileyFace() {

  // fill, circle and arc are p5.js functions

  fill('yellow');

  circle(200,200,200);

  fill('black');

  circle(160,170,30);

  circle(240,170,30);

  arc(200, 230, 80, 80, 0, PI, CHORD);

}

​

// this function is part of the p5.js library

function draw() {

  // background is part of the p5.js library

  background('black');

  // The user declared function smileyFace is

  // being called here

  smileyFace();

}