def _average(input_list: list) -> float:
    """
    Find the average of a list.

    Given a list of numbers, calculate the average of all values in the list.
    If the list is empty, default to 0.0.

    Parameters
    ----------
    input_list : list
        A ``list`` of ``floats`` to find an average of.

    Returns
    -------
    float
        Returns a ``float`` of the average value of the list.
    """
    try:
        return float(sum(input_list) / len(input_list))
    except ZeroDivisionError:
        return 0.0