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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def add_label(self, name, color):
 """Add a new label. It's id will automatically be calculated."""

        color_upper = color.upper()
        if not self._color_re.match(color_upper):
            raise ValueError('Invalid color: {}'.format(color))

        labels_tag = self.root[0]
        last_id = int(labels_tag[-1].get('id'))
        new_id = str(last_id + 1)

        new_label = etree.Element('label', id=new_id, color=color_upper)
        new_label.text = name

        labels_tag.append(new_label)