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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 downsampled_mesh(self, step):
 """Returns a downsampled copy of this mesh. Args: step: the step size for the sampling Returns: a new, downsampled Mesh object. Raises: ValueError if this Mesh has faces. """

        from lace.mesh import Mesh

        if self.f is not None:
            raise ValueError(
                'Function `downsampled_mesh` does not support faces.')

        low = Mesh()
        if self.v is not None:
            low.v = self.v[::step]
        if self.vc is not None:
            low.vc = self.vc[::step]
        return low