@property
def l_size(self):
    'The l-size is the number of black inner vertices.'
    node_dict = self.half_edge.node_dict()
    black_vertices = len([node_nr for node_nr in node_dict if (node_dict[node_nr][0].color is 'black')])
    return (black_vertices - 3)
The l-size is the number of black inner vertices.
@property
def l_size(self):
    
    node_dict = self.half_edge.node_dict()
    black_vertices = len([node_nr for node_nr in node_dict if (node_dict[node_nr][0].color is 'black')])
    return (black_vertices - 3)