<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _find_feed_language(self):
 """Find feed language based specified feed_info.txt or agency.txt. """

        self.feed_language = (
            read_first_available_value(
                os.path.join(self.src_dir, 'feed_info.txt'), 'feed_lang') or
            read_first_available_value(
                os.path.join(self.src_dir, 'agency.txt'), 'agency_lang'))
        if not self.feed_language:
            raise Exception(
                'Cannot find feed language in feed_info.txt and agency.txt')
        print('\tfeed language: %s' % self.feed_language)