* add check negative position to Read() and write tests
* add tests for Write() method
* add tests for Write() method
* add checks of whence and negative position to Seek() and write tests
* add tests for Rewind()
* add tests for Close()
* add tests for Reset()
* add tests for Len()
* add tests for Bytes()
* tests polishing
* tests polishing
* tests polishing
* tests polishing
