code: def process_formdata(self, valuelist):
          '''Replace empty values by None'''
          super(EmptyNone, self).process_formdata(valuelist)
          self.data = self.data or Nonf process_formdata(self, valuelist):
          '''Replace empty values by None'''
          super(EmptyNone, self).process_formdata(valuelist)
          self.data = self.data or None
docs: Replace empty values by None