pub unsafe extern "C" fn igraph_add_vertices(
graph: *mut igraph_t,
nv: igraph_int_t,
attr: *const igraph_attribute_record_list_t,
) -> igraph_error_tpub unsafe extern "C" fn igraph_add_vertices(
graph: *mut igraph_t,
nv: igraph_int_t,
attr: *const igraph_attribute_record_list_t,
) -> igraph_error_t