<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def main(self, function):
 """ Decorator to define the main function of the experiment. The main function of an experiment is the default command that is being run when no command is specified, or when calling the run() method. Usually it is more convenient to use ``automain`` instead. """

        captured = self.command(function)
        self.default_command = captured.__name__
        return captured