'Given an association response message, extract the OpenID
1.X session type.
This function mostly takes care of the \'no-encryption\' default
behavior in OpenID 1.
If the association type is plain-text, this function will
return \'no-encryption\'
@returns: The association type for this message
@rtype: str
@raises KeyError: when the session_type field is absent.'

def _getOpenID1SessionType(self, assoc_response):

    session_type = assoc_response.getArg(OPENID1_NS, 'session_type')
    if (session_type == 'no-encryption'):
        oidutil.log('WARNING:    OpenID    server    sent    "no-encryption"for    OpenID    1.X')
    elif ((session_type == '') or (session_type is None)):
        session_type = 'no-encryption'
    return session_type
