<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def list_users(self):
 """ Get user list from the encrypted passdb file """

        crypt = self._decrypt_file()

        self.logger.info(crypt.stderr)
        raw_userlist = crypt.stderr.split('\n')
        userlist = list()
        for index, line in enumerate(raw_userlist):
            if 'gpg: encrypted' in line:
                m = re.search('ID (\w+)', line)
                keyid = m.group(1).strip()
                userline = raw_userlist[index+1].strip()
                userlist.append((keyid, userline))
        return userlist