Node.js: returning "this" from writeHead() to allow chaining.

In Node.js version 11.10.0 and later, the writeHead() function returns "this".

test/node/write_buffer/app.js

@@ -1,6 +1,6 @@
 #!/usr/bin/env node
 
 require('unit-http').createServer(function (req, res) {
-    res.writeHead(200, {'Content-Type': 'text/plain'});
-    res.end(new Buffer([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]));
+    res.writeHead(200, {'Content-Type': 'text/plain'})
+       .end(new Buffer([0x62, 0x75, 0x66, 0x66, 0x65, 0x72]));
 }).listen(7080);