<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _verify_required_claims_exist(jwt_claims):
 """Verifies that the required claims exist. Args: jwt_claims: the JWT claims to be verified. Raises: UnauthenticatedException: if some claim doesn't exist. """

    for claim_name in [u"aud", u"exp", u"iss", u"sub"]:
        if claim_name not in jwt_claims:
            raise suppliers.UnauthenticatedException(u'Missing "%s" claim' % claim_name)