[graph-tool] vweight in BlockState

Dear list, what is the role of vweight in the constructor to BlockState? In particular, I'm trying to understand how the result of minimize_(nested_)blockmodel_dl will be different if certain vertices are assigned higher weights in the graph. I believe that if the eweight between a pair of nodes is increased, then the two nodes are more likely to end up in the same block (more or less). Would the opposite be true if their vweight is increased? Many thanks in advance, Peter