Frama-C API - Attributes
 val graph_attributes : 'a -> Graph.Graphviz.DotAttributes.graph listval default_vertex_attributes : 'a -> Graph.Graphviz.DotAttributes.vertex listval vertex_name : State.t -> stringval vertex_attributes : State.t -> Graph.Graphviz.DotAttributes.vertex listval default_edge_attributes : 'a -> Graph.Graphviz.DotAttributes.edge listval edge_attributes : (State.t * State.t) -> Graph.Graphviz.DotAttributes.edge listval get_subgraph : State.t -> Graph.Graphviz.DotAttributes.subgraph option