code: def unwrap(self, value):
          
          if value.changed('value.choices'):
              self._choices = value['value.choices']
  
          idx = value['value.index']
          ret = ntenum(idx)._store(value)
          try:
              ret.choice = self._choices[idx]
          except IndexError:
              pass # leave it as None
          return ret
docs: Unpack a Value into an augmented python type (selected from the 'value' field)