print-mobile.ts

// optimistic implementation: assume mobile.status will only have those two values
const printMobile = (mobile: Mobile) => {
  if(mobile.status === 'confirmed') {
    console.log('Your mobile is confirmed!')
  } else {
    console.warn('Your mobile is not confirmed!')
  }
}

// defensive implementation: assume mobile.status can be whatever
const printMobileAlternative = (mobile: Mobile) => {
  if(mobile.status === 'confirmed') {
    console.log('Your mobile is confirmed!')
  } else if(mobile.status === 'unconfirmed') {
    console.warn('Your mobile is not confirmed!')
  } else {
    throw new Error(`illegal state! mobile.status=${mobile.status}`)
  }
}