def _CheckDocumentId(doc_id):
 _ValidateString(doc_id, 'doc_id', MAXIMUM_DOCUMENT_ID_LENGTH)
 _ValidateVisiblePrintableAsciiNotReserved(doc_id, 'doc_id')
 return doc_id

def _CheckDocumentId ( doc_id ) : _ValidateString ( doc_id , 'doc_id' , MAXIMUM_DOCUMENT_ID_LENGTH ) _ValidateVisiblePrintableAsciiNotReserved ( doc_id , 'doc_id' ) return doc_id
checks doc_id is a valid document identifier .