def normalize( df, baseline = 0.1 ):
    """
    Normalize all spectrum.

    :param df: The Pandas DataFrame to normalize.
    :param baseline: Baseline correction threshold or False for no correction.
        [Default: 0.1]
    :returns: The normalized DataFrame.
    """
    df = df.copy()
    df /= df.max()
    if baseline is not False:
        base = df[ df.abs() < baseline ]
        df -= base.mean()

    return df