pre_set $string 'This is a trap';
pre_set $a Bare\ \$string\;;
pre_set $b 'Single-quoted \$string;';
pre_set $c "Double-quored \$string;";
a bare $a;
b bare $b;
c bare $c;
a squoted '$a';
b squoted '$b';
c squoted '$c';
a dquoted "$a";
b dquoted "$b";
c dquoted "$c";
all bare $a$b$c;
all squoted '$a$b$c';
all dquoted "$a$b$c";
bare joined with x ${a}x${b}x$c;