code: def get_attrition_in_years(self):
          
          attrition_of_nets = self.itn.find("attritionOfNets")
          function = attrition_of_nets.attrib["function"]
          if function != "step":
              return None
          L = attrition_of_nets.attrib["L"]
          return L
docs: Function for the Basic UI