"""Utility functions for the test package."""

from typing import Union


def format_number(number: Union[int, float], precision: int = 2) -> str:
    """Format a number with specified precision."""
    if isinstance(number, int):
        return str(number)
    return f"{number:.{precision}f}"


def is_even(number: int) -> bool:
    """Check if a number is even."""
    return number % 2 == 0


def factorial(n: int) -> int:
    """Calculate factorial of a number."""
    if n < 0:
        raise ValueError("Factorial is not defined for negative numbers")
    if n == 0 or n == 1:
        return 1
    return n * factorial(n - 1)