'Load a private key from a PKey object
:param pkey: The PKey object
:return: None'

def use_privatekey(self, pkey):

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