def line_up(name, number):
    ordinal_sufix: str = ""
    # for the special case when the tenths of the number is between 10 and 20
    # the ordinal of all numbers are equal to 'th'
    if number % 100 > 10 and number % 100 < 20:
        return f"{name}, you are the {number}th customer we serve today. Thank you!"
    match number % 10:
        case 1:
            ordinal_sufix = "st"
        case 2:
            ordinal_sufix = "nd"
        case 3:
            ordinal_sufix = "rd"
        case _:
            ordinal_sufix = "th"
    return f"{name}, you are the {number}{ordinal_sufix} customer we serve today. Thank you!"