if ($foo) {print "Hello"};
package Foo 1.2.3;
use Hello;
{ 1 }
next if $bar;

##</code><code>##

sideff  :       error
        |       expr
        |       expr IF expr
        |       expr UNLESS expr
        |       expr WHILE expr
        |       expr UNTIL iexpr
        |       expr FOR expr
        |       expr WHEN expr                    
        ;