def is_in_interval(num1: float, num2: float, frac: float = 0.1) -> bool:
    """Check that the num1 is in the interval defined by num2 and its fraction."""
    num2_frac = num2 * frac
    _min = num2 - num2_frac
    _max = num2 + num2_frac
    return _min <= num1 <= _max