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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 do_trace(self, arg):
 """ t - trace at the current assembly instruction trace - trace at the current assembly instruction """

        if arg:     # XXX this check is to be removed
            raise CmdError("too many arguments")
        if self.lastEvent is None:
            raise CmdError("no current thread set")
        self.lastEvent.get_thread().set_tf()
        return True