code: def alter_object(self, obj):
          
          for attname, field, replacer in self.replacers:
              currentval = getattr(obj, attname)
              replacement = replacer(self, obj, field, currentval)
              setattr(obj, attname, replacement)
docs: Alters all the attributes in an individual object.
  
          If it returns False, the object will not be saved