use Devel::Trace::Subs qw(trace trace_dump); # injected by Devel::Trace::Subs
use warnings;
use strict;

one();

exit(0);

sub one {
    trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs

    my $str = 'hello, world!';
    two($str);
}
sub two {
    trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs

    my $str = shift;
    $str =~ s/hello/goodbye/;
    three($str);
}
sub three {
    trace() if $ENV{DTS_ENABLE}; # injected by Devel::Trace::Subs

    my $str = shift;
    print "$str\n";
}