gistfile1.txt

- (void)setNoteTool:(ELBeatTool *)_noteTool_ {
  [self removeTool:(ELTool *)noteTool];
  noteTool = _noteTool_;
  [self addTool:noteTool]; **BOOM**
}

- (void)addTool:(ELTool *)_tool_ {
  if( _tool_ ) {
    [tools addObject:_tool_];
    [_tool_ addedToLayer:layer atPosition:self];

    for( NSString *keyPath in [_tool_ observableValues] ) {
      [_tool_ addObserver:self forKeyPath:keyPath options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld context:nil]; //)
    }
  }
}