GDScript: Smart Modulus

func smart_mod(dividend, divisor, sided_toward_zero : bool = false):
    # DECIMAL DIVIDEND, INTEGER DIVISOR
    # smart_mod(4.7, 3) = 1.7

    # DECIMAL DIVIDEND, DECIMAL DIVISOR
    # smart_mod(423.9, 7.49) = 11.95

    # NEGATIVE DIVIDEND
    # smart_mod(-4.7, 3, false) = 1.3
    # smart_mod(-4.7, 3, true) = -1.7

    var out : float
    if divisor == 0:
        printerr("Useful.gd, smart_mod  |  Attempted division by zero! Returning null")
        return null
    elif dividend == 0:
        return 0
    else:
        var s = sign(dividend * divisor)
        var num = abs(dividend)
        var den = abs(divisor)
        var quo = floor(num / den)
        out = s * (num - (quo * den))
        if !sided_toward_zero:
            out += den
            if out == num:
                out = 0
    return out