from dataclasses import dataclass
from math import pi

@dataclass
class Circle:
   radius: float
   @property
   def area(self) -> float:
      print("Property 'area' accessed")
      return pi * self.radius**2

class Container:
   def __init__(self, inner: Circle) -> None:
      self.inner = inner

circle = Circle(radius=4.0)
container = Container(circle)
print(container.area)

Property 'area' accessed
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
    print(container.area)
          ^^^^^^^^^^^^^^
AttributeError: 'Container' object has no attribute 'area'. Did you mean '.inner.area' instead of '.area'?