[graph-tool] Accessing all ancestors

Hello guys, I am migrating from a code devised in networkx to Graph-tool. Now, I need to get all ancestors in graph-tool. Could you guys help me out here. I found the func all_predecessors, but I could not figured out how to use it.. since it is mandatory to pass diet_map and prep_map. Can you please help me inhere :D Thanks -- O conteúdo deste e-mail e anexos são restritos aos seus destinatários e de responsabilidade do remetente. O uso do e-mail deve estar de acordo com os regulamentos institucionais vigentes.