<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def to_str(self):
 """ Returns a string of the SVG figure. """

        return etree.tostring(self.root, xml_declaration=True,
                              standalone=True,
                              pretty_print=True)