const events = {
  topics: {},
  subscribe: function(topic, listener) {
    if(!this.topics.hasOwnProperty(topic)) {
      this.topics = {
        ...this.topics,
        [topic]: []
      }
    }
    let index = this.topics[topic].push(listener) -1;
    const remove = function(topic) {
      delete this.topics[topic][index]
    }.bind(this)
    return remove;
  },
  publish: function(topic, info) {
    this.topics[topic].forEach(fn => {
      fn(info)
    })
  }
}

// TEST

const remove = events.subscribe('test', (info) => console.log(info))

events.publish('test', '1')
events.publish('test', '2')
events.publish('test', '3')
events.publish('test', '4')

remove('test')

events.publish('test', '5')