extract output variables

def extract_output(self, output_variables_list):
        """ extract output variables
        """
        variables_mapping = self.session_context.session_variables_mapping

        output = {}
        for variable in output_variables_list:
            if variable not in variables_mapping:
                logger.log_warning(
                    "variable '{}' can not be found in variables mapping, failed to output!"\
                        .format(variable)
                )
                continue

            output[variable] = variables_mapping[variable]

        utils.print_info(output)
        return output