Flow-covariance-example2.md

For context, see https://gist.github.com/jeswin/22ccd02270589c360870

/* @flow */
var http = require("http");

interface MockServer2 {
  listen(path: string) : MockServer2
}

type createServerType =  (listener?: Function) => MockServer2;

function test(cc: createServerType) {
  var p  = cc();
}

test(http.createServer);