code: def main(self, function):
          
          captured = self.command(function)
          self.default_command = captured.__name__
          return captured
docs: 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.