def normalize(self, asOf=None, multiplier=100):
    """
    Returns a normalized series or DataFrame

    Example:
        Series.normalize()

    Returns: series of DataFrame

    Parameters:
    -----------
        asOf : string
            Date format
            '2015-02-29'
        multiplier : int
            Factor by which the results will be adjusted
    """
    if not asOf:
        x0 = self.iloc[0]
    else:
        x0 = self.loc[asOf]
    return self / x0 * multiplier