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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 clean_ticker(ticker):
 """ Cleans a ticker for easier use throughout MoneyTree Splits by space and only keeps first bit. Also removes any characters that are not letters. Returns as lowercase. 'vix' 'spx' """

    pattern = re.compile('[\W_]+')
    res = pattern.sub('', ticker.split(' ')[0])
    return res.lower()