Visualise settimeout behaviour in call stack

multiple_settimeouts.js

function log(n) { console.log(n); }

setTimeout(function A() {
  setTimeout(function B() {
    log(1);
    setTimeout(function D() { log(2); }, 0);
    setTimeout(function E() { log(3); }, 0);
  }, 0);
  setTimeout(function C() {
    log(4);
    setTimeout(function F() { log(5); }, 0);
    setTimeout(function G() { log(6); }, 0);
  }, 0);
}, 0);

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