class_docstr: Mocks the `open` built-in function. A call to the instance of OpenMock returns an in-memory file which is
  readable and writable. The actual in-memory file implementation should call the passed `save_value` method
  to save the file content in the cache when the file is being closed to preserve the file content.
code: def __call__(self, file, *args, **kwargs):
      value = self.values.get(file)
      return InMemoryFile(value, self.save_value, file)
  
imports: import inspect
  import random
  import typing
  from io import StringIO
  from typing import Optional, Set, Type
  import numpy
  import albumentations
label_desc: Use image node_id 2 for calling the OpenMock obj's underlying member method code with example usage: obj.__call__(file) and returns: InMemoryFile