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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 get_properties(self):
 """ Add property to variables in XMLBIF Return ------ dict: dict of type {variable: property tag} Examples -------- {'light-on': <Element PROPERTY at 0x7f7a2ffac1c8>, 'family-out': <Element PROPERTY at 0x7f7a2ffac148>, 'hear-bark': <Element PROPERTY at 0x7f7a2ffac188>, 'bowel-problem': <Element PROPERTY at 0x7f7a2ffac0c8>, 'dog-out': <Element PROPERTY at 0x7f7a2ffac108>} """

        variables = self.model.nodes()
        property_tag = {}
        for var in sorted(variables):
            properties = self.model.node[var]
            property_tag[var] = etree.SubElement(self.variables[var], "PROPERTY")
            for prop, val in properties.items():
                property_tag[var].text = str(prop) + " = " + str(val)
        return property_tag