Function igraph_unfold_tree 

pub unsafe extern "C" fn igraph_unfold_tree(
    graph: *const igraph_t,
    tree: *mut igraph_t,
    mode: igraph_neimode_t,
    roots: *const igraph_vector_int_t,
    vertex_index: *mut igraph_vector_int_t,
) -> igraph_error_t