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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 _factory(cls, constraints, op):
 """ Factory for joining constraints with a single conjunction """

        pieces = []
        for i, constraint in enumerate(constraints):
            pieces.append(constraint)
            if i != len(constraints) - 1:
                pieces.append(op)
        return cls(pieces)