use feature qw/say/;


say exists($ENV{PERL_MYTEST})  ? "exists"          : "doesn't exist";
say defined($ENV{PERL_MYTEST}) ? "defined"         : "undefined";
say length($ENV{PERL_MYTEST})  ? "non-zero length" : "zero length";
say "<<$ENV{PERL_MYTEST}>>";

##</code><code>##

exists
defined
zero length
<<>>