Function immutable_seq::finger_tree::tree_tree

pub fn tree_tree<T, M>(left: Lazy<FingerTree<T, M>>,
                       right: Lazy<FingerTree<T, M>>)
                       -> Lazy<FingerTree<T, M>> where T: Measure<M> + 'static, M: Add<Output=M> + Zero + Copy + 'static