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'use strict';
const common = require('../common');
const EventEmitter = require('events');
const assert = require('assert');
const myEE = new EventEmitter();
var m = 0;
// This one comes last.
myEE.on('foo', common.mustCall(() => assert.equal(m, 2)));
// This one comes second.
myEE.prependListener('foo', common.mustCall(() => assert.equal(m++, 1)));
// This one comes first.
myEE.prependOnceListener('foo', common.mustCall(() => assert.equal(m++, 0)));
myEE.emit('foo');
// Verify that the listener must be a function
assert.throws(() => {
const ee = new EventEmitter();
ee.prependOnceListener('foo', null);
}, /^TypeError: "listener" argument must be a function$/);
// Test fallback if prependListener is undefined.
const stream = require('stream');
const util = require('util');
delete EventEmitter.prototype.prependListener;
function Writable() {
this.writable = true;
stream.Stream.call(this);
}
util.inherits(Writable, stream.Stream);
function Readable() {
this.readable = true;
stream.Stream.call(this);
}
util.inherits(Readable, stream.Stream);
const w = new Writable();
const r = new Readable();
r.pipe(w);
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