'Replace or set the certificate portion of the PKCS12 structure
:param pkey: The new private key.
:type pkey: :py:class:`PKey`
:return: None'

def set_privatekey(self, pkey):

    if (not isinstance(pkey, PKey)):
        raise TypeError('pkey    must    be    a    PKey    instance')
    self._pkey = pkey
