diag_stream *STDERR;
+=head2 C<THREADSAFE>
+
+This constant evaluates to true if and only if L<Test::Leaner> is thread-safe, i.e. when this version of C<perl> is at least 5.8, has been compiled with C<useithreads> defined, and L<threads> has been loaded B<before> L<Test::Leaner>.
+In that case, it also needs a working L<threads::shared>.
+
=head1 DEPENDENCIES
L<perl> 5.6.