changeClientNick method
Implementation
@override
changeClientNick({required client, required from, required to}) {
  if (_isNickInUse(to)) return false;
  _clients.remove(from);
  _clients[to] = client;
  return true;
}@override
changeClientNick({required client, required from, required to}) {
  if (_isNickInUse(to)) return false;
  _clients.remove(from);
  _clients[to] = client;
  return true;
}