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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_set(self, arg):
 """Sets the specified 'module.executable' to be the active test result to interact with. """

        if arg in self.tests:
            self.active = arg
            #Create a default argument set and analysis group for the current plotting
            if arg not in self.args:
                self.args[arg] = {"default": dict(self._template_args)}
                self.group = "default"
            else:
                self.group = list(self.curargs.keys())[0]
                
            #Change the prompt so that they know which unit test is being edited.
            self._set_def_prompt()
        else:
            msg.err("The test case '{}' is not valid.".format(arg))