Add dataclasses-exercise.py: Person class using @DataClass decorator

- Create Person class with @DataClass(frozen=True) decorator
- Use datetime.date for date_of_birth instead of int for age
- Replace manual __init__ with declarative field definitions
- Implement is_adult() method with dynamic age calculation
- Account for whether birthday has occurred this year
- Add type hints for all attributes and methods
- Include example usage with imran and eliza instances
- Demonstrate immutable dataclass with frozen=True

Author: Iswanna

prep/dataclasses-exercise.py

@@ -0,0 +1,26 @@
+from datetime import date
+from dataclasses import dataclass
+
+@dataclass(frozen=True)
+class Person:
+    name: str
+    date_of_birth: date
+    preferred_operating_system: str
+
+    def is_adult(self) -> bool:
+        today = date.today()
+        age = today.year - self.date_of_birth.year
+        
+        # Check if birthday has occurred this year
+        if (today.month, today.day) < (self.date_of_birth.month, self.date_of_birth.day):
+            age -= 1
+        
+        return age >= 18
+
+imran = Person("Imran", date(2002, 5, 15), "Ubuntu")
+print(imran.name)
+print(imran.is_adult())
+
+eliza = Person("Eliza", date(1990, 3, 20), "Arch Linux")
+print(eliza.name)
+print(eliza.is_adult())