Castling can be a bit tricky to implement. Let's break it down.

You want to check if the move is a castling attempt by verifying four conditions:

1. The king and rook are on the same rank (row).

2. The king and rook are on the same board (not across different boards, obviously!).

3. The king hasn't moved already.

4. The rook involved in castling hasn't moved already.

If these conditions are met, you can then check if there are pieces in between the king and rook.

Here's a possible approach:

1. Identify the king and rook: Determine which pieces are involved in the potential castling move.

2. Check the four conditions: Verify that the king and rook meet the requirements.

3. Check for pieces in between: If the conditions are met, check if there are any pieces between the king and rook.

You can implement this logic in your Python code using conditional statements and loops to check for pieces in between.

If you'd like, I can help you with some sample code or pseudocode to get you started. Just let me know!