themselves. Implies `--verbose`. Note that in non-bash shells,
this can cause failures in some tests which redirect and test
the output of shell functions. Use with caution.
+ Ignored in test scripts that set the variable 'test_untraceable'
+ to a non-empty value, unless it's run with a Bash version
+ supporting BASH_XTRACEFD, i.e. v4.1 or later.
-d::
--debug::