print if defined $switch{'D'};

print "$val\n" while defined($val = pop(@ary));

die "Can't readlink $sym: $!"
	unless defined($value = readlink $sym);

eval '@foo = ()' if defined(@foo);

die "No XYZ package defined" unless defined %_XYZ;

sub foo { defined &bar ? &bar(@_) : die "No bar"; }
