After 0f1d178:

• Added from __future__ import annotations, explained later
• Removed Union from imports
• Replaced all Union[A, B] with A | B
• Replaced all Optional[A] with A | None

from __future__ import annotations explaination

We needed from __future__ import annotations because of PEP 563 - Postponed Evaluation of Annotations.

Without it, Python evaluates type annotations at runtime when the module is imported. This caused the error:

def wrap(object: Dict | List, key: int | str, value: Any) -> Any | "_CollectionItem":
                                                             ^^^^^^^^^^^^^^^^^^^^^^^
TypeError: unsupported operand type(s) for |: '_AnyMeta' and 'str'

The problem: Python tried to execute Any | "_CollectionItem" at import time, but Any (from typing) doesn't support the | operator with strings.

With from __future__ import annotations:

• All annotations are stored as strings and not evaluated at import time
• They're only evaluated when explicitly needed (by type checkers, IDEs, or get_type_hints())
• This allows:
  • Forward references (like "_CollectionItem" before the class is defined)
  • Complex type expressions that might not be valid at runtime
  • Faster import times (annotations aren't evaluated)

This becomes the default behavior in Python 3.11+, but for Python 3.10 we need the __future__ import to enable it.

@vfdev-5 thanks for giving me the opportunity to work on this one! And reviewing my work so many times.