def modulo_pastel(key: int) -> str:
    """
    Select a pastel color on a modulo cycle.

    Args:
        key (int): The index modulo index.

    Returns:
        str: The selected RGB pastel color code.
    """
    hex_codes = [
        "957DAD",
        "B5EAD7",
        "C7CEEA",
        "D291BC",
        "E0BBE4",
        "E2F0CB",
        "FEC8D8",
        "FF9AA2",
        "FFB7B2",
        "FFDFD3",
    ]
    return hex_codes[key % len(hex_codes)]