anchor.diff:  [third party plugins]: https://github.com/search?q=topic%3Abuildkite-plugin&type=Repositories
   [plugin tester]: https://github.com/buildkite-plugins/plugin-tester
   [Plugin sources]: https://buildkite.com/docs/agent/v3/plugins#plugin-sources
  +[JSON Schema]: http://json-schema.org
  +[JSON Schema Lint]: https://jsonschemalint.com/
  +[Plugin Linter]: https://github.com/buildkite-plugins/buildkite-plugin-linter
  +[bksr]: https://github.com/toolmantim/bksr
  +[Understanding JSON Schema]: https://spacetelescope.github.io/understanding-json-schema/
  +[Shellcheck Plugin]: https://github.com/buildkite-plugins/shellcheck-buildkite-plugin
  
positive.code: 
  The agent parses the plugin block and passes the parameters through to the script as environment variables in the form `BUILDKITE_PLUGIN_{NAME}_{KEY}`. If a list is provided then `BUILDKITE_PLUGIN_{NAME}_{KEY}_{IDX}`.
  
  Plugins are also able to offer `command` and `environment` hooks, which aren't allowed in per-project hooks. You can use these to change how plugins execute commands.
  
  ## Security and Reliability
  
  Plugins introduce a third-party dependency in your pipeline. They provide a way to introduce executable code into your pipeline beyond scripts in your repository and access to the `pipeline.yml`.
  
  
negative.code:         workdir: /app
  ```
  
  The (simplified) logic of the [command hook][hooks] script in `hooks/command`:
  
  ```bash
  #!/bin/bash
  