Add filename suffix until file exists
    @return: filename if file is found
    @raise: ValueError if maximum suffix number is reached while searching

def getExistingFile(name, max_suffix=1000):
    """Add filename suffix until file exists
    @return: filename if file is found
    @raise: ValueError if maximum suffix number is reached while searching
    """
    num = 1
    stem, ext = os.path.splitext(name)
    filename = name
    while not os.path.exists(filename):
        suffix = "-%d" % num
        filename = stem + suffix + ext
        num += 1
        if num >= max_suffix:
            raise ValueError("No file %r found" % name)
    return filename