code: function toIsoString (date) {
    return date.getUTCFullYear()
      + '-' + pad(date.getUTCMonth() + 1)
      + '-' + pad(date.getUTCDate())
      + 'T' + pad(date.getUTCHours())
      + ':' + pad(date.getUTCMinutes())
      + ':' + pad(date.getUTCSeconds())
      + '.' + String((date.getUTCMilliseconds()/1000).toFixed(3)).slice(2, 5)
      + 'Z';
  }
docs: Turn a `date` into an ISO string.
  
  https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Date/toISOString
  
  @param {Date} date
  @return {String}