Retrieve the timestamp at which the task lease will expire. If this task has never been leased,
        it will be None. If this this task has been previously leased
        and the lease has expired, this value will be < Now().

        See: https://cloud.google.com/appengine/docs/python/taskqueue/rest/tasks

        :rtype: :class:`datetime.datetime` or ``NoneType``
        :returns: Datetime object parsed from microsecond timestamp, or
                  ``None`` if the property is not set locally. If the task has
                  not been leased, this will never be set.

def leaseTimestamp(self):
        """Retrieve the timestamp at which the task lease will expire. If this task has never been leased,
        it will be None. If this this task has been previously leased
        and the lease has expired, this value will be < Now().

        See: https://cloud.google.com/appengine/docs/python/taskqueue/rest/tasks

        :rtype: :class:`datetime.datetime` or ``NoneType``
        :returns: Datetime object parsed from microsecond timestamp, or
                  ``None`` if the property is not set locally. If the task has
                  not been leased, this will never be set.
        """
        value = self._properties.get('leaseTimestamp')
        if value is not None:
            return _datetime_from_microseconds(int(value))