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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 to_price_index(returns, start=100):
 """ Returns a price index given a series of returns. Args: * returns: Expects a return series * start (number):
 Starting level Assumes arithmetic returns. Formula is: cumprod (1+r) """

    return (returns.replace(to_replace=np.nan, value=0) + 1).cumprod() * start