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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 _sum_by_samples(seqs_freq, samples_order):
 """ Sum sequences of a metacluster by samples. """

    n = len(seqs_freq[seqs_freq.keys()[0]].freq.keys())
    y = np.array([0] * n)
    for s in seqs_freq:
        x = seqs_freq[s].freq
        exp = [seqs_freq[s].freq[sam] for sam in samples_order]
        y = list(np.array(exp) + y)
    return y