def METHOD_NAME(self):
    """Get the transformed coordinate set."""
    if self.coords is None or self.reference_coords is None:
        raise Exception("No coordinates set.")
    if self.rot is None:
        raise Exception("Nothing superimposed yet.")
    if self.transformed_coords is None:
        self.transformed_coords = dot(self.coords, self.rot) + self.tran
    return self.transformed_coords