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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 get_dual(self, constraint, ymat=None):
 """Given a solution of the dual problem and a constraint of any type, it returns the corresponding block in the dual solution. If it is an equality constraint that was converted to a pair of inequalities, it returns a two-tuple of the matching dual blocks. :param constraint: The constraint. :type index: `sympy.core.exp.Expr` :param y_mat: Optional parameter providing the dual solution of the SDP. If not provided, the solution is extracted from the sdpRelaxation object. :type y_mat: :class:`numpy.array`. :returns: The corresponding block in the dual solution. :rtype: :class:`numpy.array` or a tuple thereof. """

        if not isinstance(constraint, Expr):
            raise Exception("Not a monomial or polynomial!")
        elif self.status == "unsolved" and ymat is None:
            raise Exception("SDP relaxation is not solved yet!")
        elif ymat is None:
            ymat = self.y_mat
        index = self._constraint_to_block_index.get(constraint)
        if index is None:
            raise Exception("Constraint is not in the dual!")
        if len(index) == 2:
            return ymat[index[0]], self.y_mat[index[1]]
        else:
            return ymat[index[0]]