Properties are a great way to abstract over an internal structure

data_class_with_properties.py

from typing import List, Set

import attr


@attr.s(auto_attribs=True)
class Employee:
    name: str
    age: int
    hobbies: List[dict]  # 1

    @property
    def hobbies_names(self) -> Set[str]:  # 2
        return {hobby["name"] for hobby in self.hobbies}


def test_hobbies_names_abstracts_the_hobbies_internal_structure():
    emp = Employee(
        name="John",
        age=42,
        hobbies=[
            {"_id": "1234", "name": "Rock Climbing"},
            {"_id": "5678", "name": "Acrobatics"},
        ],
    )

    assert emp.hobbies_names == {"Rock Climbing", "Acrobatics"}  # 3