stream: add `next` and `map` utility fn (#1962)

Introduces `StreamExt` trait. This trait will be used to add utility functions
to make working with streams easier. This patch includes two functions:

* `next`: a future returning the item in the stream.
* `map`: transform each item in the stream.

1 files changed, 2 insertions, 1 deletions

diff --git a/examples/udp-codec.rs b/examples/udp-codec.rs
index 6b3f84a0..dc30394f 100644
--- a/examples/udp-codec.rs
+++ b/examples/udp-codec.rs
@@ -9,12 +9,13 @@
 #![warn(rust_2018_idioms)]
 
 use tokio::net::UdpSocket;
+use tokio::stream::StreamExt;
 use tokio::{io, time};
 use tokio_util::codec::BytesCodec;
 use tokio_util::udp::UdpFramed;
 
 use bytes::Bytes;
-use futures::{FutureExt, SinkExt, StreamExt};
+use futures::{FutureExt, SinkExt};
 use std::env;
 use std::error::Error;
 use std::net::SocketAddr;