Add generics-exercise1.py: demonstrate generic types with Person class

- Create Person dataclass with @DataClass(frozen=True) decorator
- Use List["Person"] generic type for children attribute (self-referencing)
- Implement age() method that calculates age from date_of_birth
- Add example Person instances: fatma, aisha, and imran
- Implement print_family_tree() function to display family hierarchy
- Demonstrate practical use of generics for type-safe collections
- Show how mypy validates generic type parameters

Author: Iswanna

prep/generics-exercise1.py

@@ -0,0 +1,30 @@
+from dataclasses import dataclass
+from typing import List
+from datetime import date
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    date_of_birth: date
+    children: List["Person"]
+
+    def age(self) -> int:
+        today = date.today()
+        age = today.year - self.date_of_birth.year
+        if (today.month, today.day) < (self.date_of_birth.month, self.date_of_birth.day):
+            age -= 1
+        return age
+
+fatma = Person(name="Fatma", date_of_birth=date(2015, 7, 22), children=[])
+aisha = Person(name="Aisha", date_of_birth=date(2018, 3, 10), children=[])
+
+imran = Person(name="Imran", date_of_birth=date(1985, 5, 15), children=[fatma, aisha])
+
+def print_family_tree(person: Person) -> None:
+    print(person.name)
+    for child in person.children:
+        print(f"- {child.name} ({child.age()})")
+
+print_family_tree(imran)
+
+