Fixes for observe method

[lekhmanrus]

• returned event, not events array
• fixed condition for exact match keys
• removed unused imports

[lekhmanrus]

My mistake. don't apply commit b3b175a. sorry

[DanielKucal]

Why? It doesn't make sens to add Config.prefix to the key below if the key already starts with prefix...

[lekhmanrus]

Tbh, I don't remember exactly why I did that... but I suppose, it is because event.key is a key without prefix, and that fix is to observe key without prefix, so, for example:
Before:

if (exactMatch) {
  if (key.startsWith(Config.prefix)) {
  // if ('test'.startsWith('im.')) { // false
    return event.key === key;
  }
  return event.key === Config.prefix + key;
  // return 'test' === 'im.' + 'test'; // false
}

After:

if (exactMatch) {
  if (!key.startsWith(Config.prefix)) {
  // if (!'test'.startsWith('im.')) { // true
    return event.key === key;
    // return 'test' === 'test'; // true
  }
  return event.key === Config.prefix + key;
}

But it won't work for key with prefix in both cases - Example 2:
Before:

if (exactMatch) {
  if (key.startsWith(Config.prefix)) {
  // if ('im.test'.startsWith('im.')) { // true
    return event.key === key;
    // return 'test' === 'im.test'; // false
  }
  return event.key === Config.prefix + key;
}

After:

if (exactMatch) {
  if (!key.startsWith(Config.prefix)) {
  // if (!'im.test'.startsWith('im.')) { // false
    return event.key === key;
  }
  return event.key === Config.prefix + key;
  // return 'test' === 'im.' + 'im.test'; // false
}

But I don't remember exactly. It was a while ago.