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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def tokenize(s):
 """ Tokenize a string by splitting it by + and - ['this', 'PLUS', 'that'] ['this', 'PLUS', 'that'] ['this', 'PLUS', 'that', 'MINUS', 'other'] """


    # Crude tokenization
    s = s.replace('+', ' PLUS ').replace('-', ' MINUS ') \
        .replace('/', ' DIVIDE ').replace('*', ' MULTIPLY ')
    words = [w for w in s.split(' ') if w]
    return words