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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 is_solved(self):
 """ Check if Cube's F2L is solved. """

        if self.cube.D == [[Square(self.cube["D"].colour)] * 3] * 3:
            for face in "LFRB":
                if self.cube.get_face(face)[1:] != [[Square(self.cube[face].colour)] * 3] * 2:
                    return False
            return True
        return False