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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 combine(self, merge_points=False):
 """Appends all blocks into a single unstructured grid. Parameters merge_points : bool, optional Merge coincidental points. """

        alg = vtk.vtkAppendFilter()
        for block in self:
            alg.AddInputData(block)
        alg.SetMergePoints(merge_points)
        alg.Update()
        return wrap(alg.GetOutputDataObject(0))