code: def _joinclass(codtuple):
      
      if not isinstance(codtuple, tuple):
          raise TypeError("argument must be tuple, was %s" % type(codtuple))
      if len(codtuple) != 3:
          raise ValueError("tuple must have 3 items, has %d" % len(codtuple))
  
      serviceclass = codtuple[0] << 2 << 11
      majorclass = codtuple[1] << 2 << 6
      minorclass = codtuple[2] << 2
      return (serviceclass | majorclass | minorclass)
docs: The opposite of splitclass(). Joins a (service, major, minor) class-of-
      device tuple into a whole class of device value.