text: import t from 'assert-op'
  import derange from '../util/derange.js'
  
  t('uniquely deranged', a => {
  	const set = new Set,
  				fcn = derange(5)
  	for (let i=0; i<120; ++i) {
  		let val = fcn().join('')
  		if (set.has(val)) throw Error('not unique')
  		set.add(val)
  	}
  })
  t('individualy deranged', a => {
  	const fcn = derange(5)
  	let last = fcn().slice()
  	for (let i=0; i<119; ++i) {
  		let val = fcn()
  		for (let j=0; j<5; ++j) if (last[j] === val[j]) throw Error('not deranged enough')
  		last = fcn().slice()
  	}
  })
  