Simplify S3.open_file with "with" form
Simplify S3.open_file with "with" form

asciinema/asciinema.org,asciinema/asciinema.org,asciinema/asciinema.org,asciinema/asciinema-server,asciinema/asciinema.org,asciinema/asciinema-server,asciinema/asciinema-server,asciinema/asciinema-server