class_docstr: A descriptor that provides a slot.
  
  This is useful for types that can't have slots via __slots__,
  e.g. tuple subclasses.
code: def __get__(self, obj, cls):
      if obj is None:  # called on the class
          return self
      try:
          value = self.instances[id(obj)]
      except KeyError:
          if self.initial is _NOT_SET:
              value = self.default
          else:
              value = self.initial
          self.instances[id(obj)] = value
      if value is _NOT_SET:
          raise AttributeError(self.name)
      # XXX Optionally make a copy?
      return value
  
file_path: cpython/Tools/c-analyzer/c_common/clsutil.py
label_desc: Use image node_id 3 for calling the Slot obj's underlying member method code with example usage: obj.__get__(obj, cls) and returns: value, self