SOURCE

var assert = (value, text) => {
  if(value === true) {
    console.log(text)
  } else{
    console.log('error')
  }
}
const ninjas = []
ninjas.push('kuma')
assert(ninjas[0] === 'kuma', 'kuma is the first item in the array')
assert(ninjas.length === 1, 'we hava one item in the array')

ninjas.push('Hattori')
assert(ninjas.length === 2,'length is 2')
console.log(ninjas)

ninjas.unshift('Yagyu')
console.log(ninjas.length)

assert(ninjas[0] === "Ya")