'Store tag data and return a placeholder.'

def store_tag(self, tag, attrs, left_index, right_index):

    self.tag_data.append({u'tag': tag, u'attrs': attrs, u'left_index': left_index, u'right_index': right_index})
    placeholder = (TAG_PLACEHOLDER % str(self.tag_counter))
    self.tag_counter += 1
    return placeholder
