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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 add_text(self, coords, text, color=(0, 0, 0)):
 """ Add text at a coordinate. Args: coords: Coordinates to add text at. text: Text to place. color: Color for text as RGB. Defaults to black. """

        source = vtk.vtkVectorText()
        source.SetText(text)
        mapper = vtk.vtkPolyDataMapper()
        mapper.SetInputConnection(source.GetOutputPort())
        follower = vtk.vtkFollower()
        follower.SetMapper(mapper)
        follower.GetProperty().SetColor(color)
        follower.SetPosition(coords)
        follower.SetScale(0.5)
        self.ren.AddActor(follower)
        follower.SetCamera(self.ren.GetActiveCamera())