def _expand_short_hex(hex_color: str) -> str:
    """
    Expands a short hexadecimal color value to the full 6-digit hexadecimal color value.

    Args:
        hex_color (str): The short hexadecimal color value to expand.

    Returns:
        str: The expanded 6-digit hexadecimal color value.
    """
    # If the hex color is not a short hexadecimal color value, return the original value
    if not _is_short_hex(color=hex_color):
        return hex_color

    # Get the hex color without the leading '#'
    hex_color = hex_color[1:]

    # Return the expanded 6-digit hexadecimal color value
    expanded = "#" + "".join(x * 2 for x in hex_color)
    expanded = expanded.upper()
    return expanded

    Expands a short hexadecimal color value to the full 6-digit hexadecimal color value.

    Args:
        hex_color (str): The short hexadecimal color value to expand.

    Returns:
        str: The expanded 6-digit hexadecimal color value.
    
great_tables/_data_color/base.py