export function uuid () {
  var s = []
  var hexDigits = '0123456789abcdef'
  for (var i = 0; i < 36; i++) {
    s[i] = hexDigits.substr(Math.floor(Math.random() * 0x10), 1)
  }
  s[14] = '4' // bits 12-15 of the time_hi_and_version field to 0010
  s[19] = hexDigits.substr((s[19] & 0x3) | 0x8, 1) // bits 6-7 of the clock_seq_hi_and_reserved to 01
  s[8] = s[13] = s[18] = s[23] = '-'

  var uuid = s.join('')
  return uuid
}
