<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def transformMesh(self, transformation):
 """ Apply this transformation to the polygonal `mesh`, not to the actor's transformation, which is reset. :param transformation: ``vtkTransform`` or ``vtkMatrix4x4`` object. """

        if isinstance(transformation, vtk.vtkMatrix4x4):
            tr = vtk.vtkTransform()
            tr.SetMatrix(transformation)
            transformation = tr

        tf = vtk.vtkTransformPolyDataFilter()

        tf.SetTransform(transformation)
        tf.SetInputData(self.polydata())
        tf.Update()
        self.PokeMatrix(vtk.vtkMatrix4x4())  # identity
        return self.updateMesh(tf.GetOutput())