Function igraph_get_subisomorphisms_vf2_callback 

pub unsafe extern "C" fn igraph_get_subisomorphisms_vf2_callback(
    graph1: *const igraph_t,
    graph2: *const igraph_t,
    vertex_color1: *const igraph_vector_int_t,
    vertex_color2: *const igraph_vector_int_t,
    edge_color1: *const igraph_vector_int_t,
    edge_color2: *const igraph_vector_int_t,
    map12: *mut igraph_vector_int_t,
    map21: *mut igraph_vector_int_t,
    isohandler_fn: igraph_isohandler_t,
    node_compat_fn: igraph_isocompat_t,
    edge_compat_fn: igraph_isocompat_t,
    arg: *mut c_void,
) -> igraph_error_t