Where is markobject.doc referenced in pickletools?

In the documentation for the MARK opcode in pickletools.py, it references a markobject.doc file (line), but I can’t find it anywhere. Does anyone have any idea what this refers to?

  1. This link has a list of pickle opcodes including MARK.
  2. This might also help but seems a bit older.

This search /where is the file markobject.doc file for Pyton pickle opcode/ returned a few links. This one did not /where is the file +markobject.doc file for Pyton pickle opcode/.

Yeah, I’ve been going through the source code for Pickle working on updating/modifying the documentation for each opcode. I’m looking specifically for that DOC file; I’m guessing the document is SUPER old, but just wondering if it’s still around.