[graph-tool] Inverted keyword argument in GraphView

Hi, I have a graph with two types of nodes. This is specified via the boolean vertex property `is_typeA`. I currently have code like: ``` typeA_graph = graph_tool.GraphView(my_graph, vfilt=is_typeA) ``` I'd like to create an `typeB_graph` GraphView, too. The condition obviously is that the node is _not_ typeA. However, I don't see an inverted keyword argument like in the `set_vertex_filter()` function. Is there a possibility to get that? Best, Gerion