optional.py

from typing import Optional

def process_data(file_path: str, delimiter: Optional[str] = None) -> str:
    delimiter_info = f" with delimiter '{delimiter}'" if delimiter else ""
    return f"Processing file at {file_path}{delimiter_info}"

print(process_data("/path/to/file.csv"))  # Output: Processing file at /path/to/file.csv
print(process_data("/path/to/file.csv", ","))  # Output: Processing file at /path/to/file.csv with delimiter ','