code: def command(self, function=None, prefix=None, unobserved=False):
          
          captured_f = self.capture(function, prefix=prefix)
          captured_f.unobserved = unobserved
          self.commands[function.__name__] = captured_f
          return captured_f
docs: Decorator to define a new command for this Ingredient or Experiment.
  
          The name of the command will be the name of the function. It can be
          called from the command-line or by using the run_command function.
  
          Commands are automatically also captured functions.
  
          The command can be given a prefix, to restrict its configuration space
          to a subtree. (see ``capture`` for more information)
  
          A command can be made unobserved (i.e. ignoring all observers) by
          passing the unobserved=True keyword argument.