docs: def cmd(*args, **kwargs):
      """Decorate a callable to replace it with a manufactured command
      class.
  
      Extends the interface of ``CommandDecorator``, allowing the same
      ``cmd`` to be used as a decorator or as a decorator factory::
  
          @cmd(root=True)
          def build():
              ...
  
          @build.register
          @cmd
          def deploy():
              ...
  
      Further enables composition of configuration, for example via
      partials, as helpers.
  
      """
      try:
          (first, *remainder) = args
      except ValueError:
          pass
      else:
          if callable(first):
              return CommandDecorator(*remainder, **kwargs)(first)
  
      return CommandDecorator(*args, **kwargs)