def get_multiples_of_n(n: int, limit: int) -> str:
    """
    Returns a string with multiples of a given number up to a specified limit.
    Use a loop to collect positive multiples, starting at n. Separate them
    with a comma and one space, without a trailing separator.

    Parameters
    ----------
    n : int
        The positive number whose multiples are to be collected.
    limit : int
        The upper limit for the multiples (inclusive).

    Returns
    -------
    str
        String with multiples of n, or an empty string if limit is below n.

    Examples
    --------
    >>> get_multiples_of_n(3, 10)
    '3, 6, 9'
    >>> get_multiples_of_n(2, 4)
    '2, 4'
    """
    raise NotImplementedError("Replace this line with your code.")