def to_xml(self, xml_parent):
    origin = SubElement(xml_parent, 'origin')
    origin.set('xyz', '{0} {1} {2}'.format(self.x, self.y, self.z))
    origin.set('rpy', '{0} {1} {2}'.format(self.roll, self.pitch, self.yaw))
    return origin
def to_xml(self, xml_parent):
    origin = SubElement(xml_parent, 'origin')
    origin.set('xyz', '{0} {1} {2}'.format(self.x, self.y, self.z))
    origin.set('rpy', '{0} {1} {2}'.format(self.roll, self.pitch, self.yaw))
    return origin