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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 __create(self, opcode):
 """This method returns the appropriate class object corresponding to the passed opcode."""

        tftpassert(opcode in self.classes,
                   "Unsupported opcode: %d" % opcode)

        packet = self.classes[opcode]()

        return packet