method to use when forward tag is encountered in musicXML. jumps forward in the bar by <duration>
        :param duration: number of beats to move forward
        :return:

def Forward(self, duration=0):
        '''
        method to use when forward tag is encountered in musicXML. jumps forward in the bar by <duration>
        :param duration: number of beats to move forward
        :return:
        '''
        for voice in self.GetChildrenIndexes():
            voice_obj = self.getVoice(voice)
            if voice_obj.GetChild(self.index) is None:
                voice_obj.AddChild(NoteNode.NoteNode(duration=duration))
        self.index += 1