old_contents: from merfi import base, util
  from tambo import Transport
  
  
  class BaseBackend(base.BaseCommand):
  
      options = []
      parser = None
  
      def parse_args(self):
          self.parser = Transport(self.argv, options=self.options)
          self.parser.catch_help = self.help()
          self.parser.parse_args()
          self.path = util.infer_path(self.parser.unkown_commands)
          self.check_dependency()
          self.sign()
  
      def sign(self):
          raise NotImplemented()
  
new_contents: from merfi import base, util
  from tambo import Transport
  
  
  class BaseBackend(base.BaseCommand):
  
      options = []
      parser = None
  
      def parse_args(self):
          self.parser = Transport(self.argv, options=self.options)
          self.parser.catch_help = self.help()
          self.parser.parse_args()
          self.path = util.infer_path(self.parser.unknown_commands)
          self.check_dependency()
          self.sign()
  
      def sign(self):
          raise NotImplemented()
  
subject: fix typo on unknown, requires new tambo