Generated by XState Viz: https://xstate.js.org/viz

machine.js

const SignalMachine = Machine({
  id: 'signal',
  initial: 'red',
  states: {
    red: {
      on: {
        TIMER: 'green',
      },
      after: {
        1000: 'green',
      },
    },
    green: {
      on: {
        TIMER: 'yellow',
      },
      after: {
        1000: 'yellow',
      },
    },
    yellow: {
      on: {
        TIMER: 'red',
      },
      after: {
        1000: 'red',
      },
    },
  },
})