def add_verbs(g, verb_list, vertex_shapes, vertex_names):
    """
    Accepts a graph-tool graph object and a list of verbs to add as vertices in the graph.
    Updates the vertex_shapes vertex property map to make each verb a square
    Updates the vertex_name vertex property map to assign each verb string as a name for each vertex
    Creates a vertex_dict that can be used to lookup the vertex ID of a given verb string    
    """
    vertex_verb_dict = {}
    for vertex in verb_list:
        v = g.add_vertex()
        vertex_shapes[v] = 'square'
        vertex_names[v] = vertex
        vertex_verb_dict.update({vertex:int(v)})
    return g, vertex_verb_dict