Function nctree_add 

pub unsafe extern "C" fn nctree_add(
    n: *mut nctree,
    spec: *const c_uint,
    add: *const nctree_item,
) -> c_int

Insert |add| into the nctree |n| at |spec|. The path up to the last element must already exist. If an item already exists at the path, it will be moved to make room for |add|.