text: """Collection of attrs conversion functions and validators."""
  import datetime
  
  import attr
  
  NOT_PROVIDED = object()
  
  
  def isodatetime(value):
      if value is NOT_PROVIDED:
          return value
  
      date = datetime.datetime.strptime(value, '%Y-%m-%dT%H:%M:%SZ')
      return date.replace(tzinfo=UTC())
  
  
  def aliased(json_key, **kwargs):
      kwargs.setdefault('metadata', {})
      kwargs['metadata']['json_key'] = json_key
      return attr.ib(**kwargs)
  
  
  class UTC(datetime.tzinfo):
  
      """Yet another UTC reimplementation, to avoid a dependency on pytz or
      dateutil."""
  
      ZERO = datetime.timedelta(0)
  
      def __repr__(self):
          return 'UTC()'
  
      def dst(self, dt):
          return self.ZERO
  
      def tzname(self, dt):
          return 'UTC'
  
      def utcoffset(self, dt):
          return self.ZERO
  