Function igraph_neighbors 

pub unsafe extern "C" fn igraph_neighbors(
    graph: *const igraph_t,
    neis: *mut igraph_vector_int_t,
    vid: igraph_int_t,
    mode: igraph_neimode_t,
    loops: igraph_loops_t,
    multiple: igraph_bool_t,
) -> igraph_error_t