'Provides HTTP_X_TIMESTAMP as a :class:`~swift.common.utils.Timestamp`'

@property
def timestamp(self):

    if (self._timestamp is None):
        try:
            raw_timestamp = self.environ['HTTP_X_TIMESTAMP']
        except KeyError:
            raise InvalidTimestamp('Missing    X-Timestamp    header')
        try:
            self._timestamp = Timestamp(raw_timestamp)
        except ValueError:
            raise InvalidTimestamp('Invalid    X-Timestamp    header')
    return self._timestamp
