Common sorted list

put sort keys [∪] [5,1,3,8,9,4,8,7], [3,5,9,8,4], [1,3,7,9];
put sort keys [∪] [5,1,3,8,9,4,8,7], [3,5,9,8,4], [1,3,7,9], [<not everything is an integer so why not avoid special cases # ~ 23 4.2>];

Output:

1 3 4 5 7 8 9
# 1 3 4 4.2 5 7 8 9 23 an avoid cases everything integer is not so special why ~