'Adjust the time stamp for when the certificate stops being valid
:param amount: The number of seconds by which to adjust the ending
validity time.
:type amount: :py:class:`int`
:return: None'

def gmtime_adj_notAfter(self, amount):

    if (not isinstance(amount, int)):
        raise TypeError('amount    must    be    an    integer')
    notAfter = _lib.X509_get_notAfter(self._x509)
    _lib.X509_gmtime_adj(notAfter, amount)
