def privacy_check(postal_code: str) -> bool:
    """
    Helper function for the callbacks.
    Checks if postal code is private.
    ---
    Args: 
        postal_code (str): Area postal code.

    Returns: 
        True (bool): When postal code is in the private_list
        False (bool): When postal code is not found in the private_list
    """
    # List of private area postcodes
    private_list = ['00230', '02290', '01770']

    if postal_code in private_list:
        return True
    else:
        return False