from typing import Optional
from typing import Dict


def create_exclusive_start_key(player_id: str, start_key: Optional[str]) -> Optional[Dict[str, str]]:
    """
    Create the 'ExclusiveStartKey' parameter for the DynamoDB query, based on the user-provided 'start_key' parameter to
    this Lambda function.
    """
    if start_key:
        return {
            'player_id': player_id,
            'slot_name': start_key,
        }
    else:
        return None