class_docstr: Base class for stub image loaders.
  
  A stub loader is an image loader that can identify files of a
  certain format, but relies on external code to load the file.
code: def load(self):
      loader = self._load()
      if loader is None:
          raise OSError(
              f"cannot find loader for this {self.format} file"
          )
      image = loader.load(self)
      assert image is not None
      # become the other object (!)
      self.__class__ = image.__class__
      self.__dict__ = image.__dict__
  
imports: import io
  import itertools
  import struct
  import sys
  from .None import Image
  from ._util import isPath
label_desc: Use image node_id 2 for calling the StubImageFile obj's underlying member method code with example usage: obj.load() without return types