DEPRECATED

Please, use https://www.npmjs.com/package/@nodeart/event_emitter instead.

Methods:

observable.on(eventName, ...fns)
observable.once(eventName, ...fns)
observable.unbind(eventName, ...fns) 
observable.unbindAll()
// One can remove some functions from listeners array,
// but to remove all listeners (read 'remove event'), one can pass
// only eventName to .unbind method
observable.emit(eventName, ...args)

Features:

1. any number of functions can be put as listeners
2. chaining available
3. written with ES6 syntax
4. can be used in node.js and in browser