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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 plot_curvature(self, curv_type='mean', **kwargs):
 """ Plots the curvature of the external surface of the grid Parameters curv_type : str, optional One of the following strings indicating curvature types - mean - gaussian - maximum - minimum **kwargs : optional Optional keyword arguments. See help(vtki.plot) Returns ------- cpos : list Camera position, focal point, and view up. Used for storing and setting camera view. """

        trisurf = self.extract_surface().tri_filter()
        return trisurf.plot_curvature(curv_type, **kwargs)