* make output_dir optional
* inintaied a basic testing module to validate and verify the changes
* Test output_dir default to 'tmp_trainer' when unspecified.
* test existing functionality of output_dir.
* test that output dir only created when needed
* final check
* added doc string and changed the tmp_trainer to trainer_output
* amke style fixes to test file.
* another round of fixup
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Co-authored-by: sambhavnoobcoder <indosambahv@gmail.com>
