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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 mzminus(df, minus=0, noise=10000):
 """ The abundances of ions which are minus below the molecular ion. """

    mol_ions = ((df.values > noise) * df.columns).max(axis=1) - minus
    mol_ions[np.abs(mol_ions) < 0] = 0
    d = np.abs(np.ones(df.shape) * df.columns -
               (mol_ions[np.newaxis].T * np.ones(df.shape))) < 1
    d = (df.values * d).sum(axis=1)
    return Trace(d, df.index, name='m-' + str(minus))