def add_to_params(self, parameters, value):
        if value:
            path = os.path.expandvars(value)
            path = os.path.expanduser(path)
            if os.path.isfile(path):
                self._key_path = path
                endpoint_prefix = \
                    self._operation_model.service_model.endpoint_prefix
                event = 'after-call.%s.%s' % (endpoint_prefix,
                                              self._operation_model.name)
                self._session.register(event, self._decrypt_password_data)
            else:
                msg = ('priv-launch-key should be a path to the '
                       'local SSH private key file used to launch '
                       'the instance.')
                raise ValueError(msg)
Initialise a PayloadCrypter object.
dataset/ETHPy150Open aws/aws-cli/awscli/customizations/ec2decryptpassword.py/LaunchKeyArgument.add_to_params--crossover with--dataset/ETHPy150Open isislovecruft/obfsproxy/obfsproxy/transports/scramblesuit/mycrypto.py/PayloadCrypter.__init__