@property
def value(self):
    _value = self._context
    for n in self._names:
        if (n not in _value):
            return None
        _value = _value[n]
    return _value
@property
def value(self):
    _value = self._context
    for n in self._names:
        if (n not in _value):
            return None
        _value = _value[n]
    return _value