'Change the timestamp for when the certificate starts being valid to the current
time plus an offset.
:param amount: The number of seconds by which to adjust the starting validity
time.
:return: None'

def gmtime_adj_notBefore(self, amount):

    if (not isinstance(amount, int)):
        raise TypeError('amount    must    be    an    integer')
    notBefore = _lib.X509_get_notBefore(self._x509)
    _lib.X509_gmtime_adj(notBefore, amount)
