```ruby
#!/usr/bin/env ruby
require './gen_template.rb'

gen_template(
  arch: "x86_64",
  iso_url: "https://nixos.org/releases/nixos/15.09/nixos-15.09.1076.9220f03/nixos-minimal-15.09.1076.9220f03-x86_64-linux.iso",
  iso_sha256: "77bd77859f937da23e9a45ccf50410ae32a41400e3b9ca3a8de212821b641c88",
  virtualbox_guest_os: "Linux_64",
)
```

Update x86_64 template to 16.03
user
```ruby
#!/usr/bin/env ruby
require './gen_template.rb'

gen_template(
  arch: "x86_64",
  iso_url: "https://nixos.org/releases/nixos/16.03/nixos-16.03.1271.546618c/nixos-minimal-16.03.1271.546618c-x86_64-linux.iso",
  iso_sha256: "81c91427d7fd384097a8a811715f69379a81c3da02c7db39ec85f4a11f2d42f0",
  virtualbox_guest_os: "Linux_64",
)
```
assistant