Convert a number to the roman numeral equivalent.

    Syntax: {command} [number]

def cmd(send, msg, _):
    """Convert a number to the roman numeral equivalent.

    Syntax: {command} [number]

    """
    if not msg:
        msg = randrange(5000)
    elif not msg.isdigit():
        send("Invalid Number.")
        return
    send(gen_roman(int(msg)))