example.py

# example.py — Batch 12

# --- 1. *args unpacking in calls ---
def add3(a: int, b: int, c: int) -> int:
    return a + b + c

def test_star_unpack() -> int:
    nums: list[int] = [10, 20, 30]
    return add3(*nums)  # 60

# --- 2. *args partial unpack f(x, *lst) ---
def test_star_partial() -> int:
    rest: list[int] = [2, 3]
    return add3(1, *rest)  # 6

# --- 3. __iter__ / __next__ user iterator ---
class Range:
    cur: int
    stop: int
    def __init__(self, stop: int) -> None:
        self.cur = 0
        self.stop = stop
    def __iter__(self) -> "Range":
        return self
    def __next__(self) -> int:
        if self.cur >= self.stop:
            raise StopIteration()
        self.cur = self.cur + 1
        return self.cur

def test_user_iter() -> int:
    total: int = 0
    for x in Range(5):
        total = total + x
    return total  # 1+2+3+4+5 = 15

# --- 4. raise / catch StopIteration ---
def test_stop_iteration() -> int:
    r: Range = Range(2)
    a: int = r.__next__()  # 1
    b: int = r.__next__()  # 2
    try:
        r.__next__()       # raises StopIteration
    except StopIteration:
        return a + b       # 3
    return 0

if __name__ == "__main__":
    print("star_unpack:", test_star_unpack())
    print("star_partial:", test_star_partial())
    print("user_iter:", test_user_iter())
    print("stop_iteration:", test_stop_iteration())