pub unsafe extern "C" fn igraph_stack_bool_push(
s: *mut igraph_stack_bool_t,
elem: igraph_bool_t,
) -> igraph_error_tpub unsafe extern "C" fn igraph_stack_bool_push(
s: *mut igraph_stack_bool_t,
elem: igraph_bool_t,
) -> igraph_error_t