def multiply(intf, ints):
    """
    overpython.multiply(intf, ints)
    
    Multiply intf by ints. Raises ValueError if intf/ints is a string.
    """
    try:
        return float(intf) * float(ints)
    except ValueError:
        raise ValueError('%s/%s is not a number' % (intf, ints))
