pub unsafe extern "C" fn igraph_are_adjacent(
graph: *const igraph_t,
v1: igraph_int_t,
v2: igraph_int_t,
res: *mut igraph_bool_t,
) -> igraph_error_tpub unsafe extern "C" fn igraph_are_adjacent(
graph: *const igraph_t,
v1: igraph_int_t,
v2: igraph_int_t,
res: *mut igraph_bool_t,
) -> igraph_error_t