# data handler

# logic
class Location:
    def __init__(self, name, units):
        self.name = name
        self.units = units

    def update(self):
        # slome logic
        self.units.append("unit_after_update")

# visualization handler
class Screen:
    def __init__(self, name, location):
        self.name = name
        self.location = location

    def update(self):
        print("updating")
        self.location.update()

    def __repr__(self):
        return f"{self.name} units:{self.location.units}"


loc = Location("location_1", ["unit_1",])
scr = Screen("temp", loc)
print(scr)
scr.update()
scr.update()
print(scr)