# import VietnameseTextNormalizer

def preprocess(text):
    text = text.lower().split("\n") # text = VietnameseTextNormalizer.Normalize(text.lower()).split("\n")
    lines = []
    for t in text:
        t = t.replace(".", " . ")
        t = t.replace("!", " . ")
        t = t.replace("?", " . ")
        t = t.replace(",", " , ")
        
        t = t.rstrip().strip()
        lines.append(t)
    return ' . '.join(lines)