def strerror(errclass, errcode):
    if (errclass == ERRCLASS_OS):
        return ('OS Error', str(errcode))
    elif (errclass == ERRCLASS_QUERY):
        return ('Query Error', QUERY_ERRORS.get(errcode, 'Unknown error'))
    elif (errclass == ERRCLASS_SESSION):
        return ('Session Error', SESSION_ERRORS.get(errcode, 'Unknown error'))
    else:
        return ('Unknown Error Class', 'Unknown Error')
def strerror(errclass, errcode):
    if (errclass == ERRCLASS_OS):
        return ('OS Error', str(errcode))
    elif (errclass == ERRCLASS_QUERY):
        return ('Query Error', QUERY_ERRORS.get(errcode, 'Unknown error'))
    elif (errclass == ERRCLASS_SESSION):
        return ('Session Error', SESSION_ERRORS.get(errcode, 'Unknown error'))
    else:
        return ('Unknown Error Class', 'Unknown Error')