>perl -E"@a[4..99] = ();  say 0+@a;"
100

>perl -E"for (@a[4..99]) {}  say 0+@a;"
100

>perl -E"sub {}->(@a[4..99]);  say 0+@a;"
100

>perl -E"grep 1, @a[4..99];  say 0+@a;"
100