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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 fit(self, sequences, y=None):
 """Fit a PCCA lumping model using a sequence of cluster assignments. Parameters sequences : list(np.ndarray(dtype='int')) List of arrays of cluster assignments y : None Unused, present for sklearn compatibility only. Returns ------- self """

        super(PCCA, self).fit(sequences, y=y)
        self._do_lumping()
        return self