src/module.js
function inject(target, source) {
    for (var k in source.prototype) {
        target.prototype[k] = source.prototype[k];
    }
}
function inject(target, source) {
    for (var k in source.prototype) {
        target.prototype[k] = source.prototype[k];
    }
}
function inject ( target , source ) { for ( var k in source . prototype ) { target . prototype [ k ] = source . prototype [ k ] ; } }
turn the stream into an event emitter
turn the stream into an event emitter