command /gm <text>:
        if arg-1 is "creative" or "c":
            set player's gamemode to creative
        if arg-1 is "survival" or "s":
            set player's gamemode to survival
        if arg-1 is "spectator" or "sp":
            set player's gamemode to spectator
        if arg-1 is "adventure" or "a":
            set player's gamemode to adventure