Slowly print lines, for testing command line interfaces

slowprint.py

#!/usr/bin/env python3
"""
Print lines slowly

Intended for testing command line interfaces
"""

import argparse
import itertools
import time
from collections.abc import Iterable


def print_slowly(amount: int | None, /, *, delay: float) -> None:
    source: Iterable[int]
    if amount is None:
        source = itertools.count(1)
    else:
        source = range(1, amount + 1)

    for index in source:
        time.sleep(delay)
        print("Line", index)


def main() -> None:
    parser = argparse.ArgumentParser(
        prog="slowprint", description="Prints lines slowly"
    )
    parser.add_argument(
        "amount",
        help="The number of lines to print, infinite if unspecified",
        nargs="?",
        type=int,
    )
    parser.add_argument(
        "-d",
        "--delay",
        help="The seconds to wait between printing each line",
        type=float,
        default=1,
    )
    args = parser.parse_args()

    print_slowly(args.amount, delay=args.delay)


if __name__ == "__main__":
    main()