def _number_of_arguments_in_list(ctx, *what):
    """
    Return the number of `what` found as `ctx` dict keys with a value
    other than `None`.

    :param ctx: Arguments to check.
    :type ctx: dict

    :param what: List of arguments corresponding to `ctx` keys.
    :type what: list

    """
    return sum(1 for w in what if ctx.get(w) is not None)
