code: def command_template(self):
          
          com_out = self.appname
          for key, val in self.args.items():
              if key in self._options:
                  com_out += ' %s={%s}' % (key, key)
              else:
                  com_out += ' %s=%s' % (key, val)
          return com_out
docs: Build and return a string that can be used as a template invoking
          this chain from the command line.
  
          The actual command can be obtainted by using
          `self.command_template().format(**self.args)`