I was looking for a way to prevent adding of parallel edges in the graph i.e. I would like to create a graph that is not a multigraph. Now I do that manually but that is quite prone to bugs. 

Is this possible to do this with graph tool in any way?

The option I would like is the one like the option that boost graph has i.e. graph_traits<adjacency_list>::edge_parallel_category

that can be found on:

Thanks!

Aleks