Inherit Coder from coders.

[robertwb]

It'd really be better to not use a Coder here at all, but this at least fixes the breakage.

Please, go through these steps before you submit a PR.

1. Make sure that your PR is not a duplicate.

2. Before submitting the PR, review your changes:

   • Adjust the code to the existing style.
   • Add a set of unit tests for the changes and ensure they all pass.
   • Add accompanying README.md file with instructions on usage. See awesome-readme for good examples of high-quality READMEs.
   • Add a link to your contribution in the top-level README (alpha-order).
   • Add Apache 2.0 license headers with an up-to-date copyright date attributed to Google LLC.
   • Remove unnecessary LICENSE files. There's no need to include an additional license since all repository submissions are covered by the top-level Apache 2.0 license.

3. After these steps, you're ready to open a pull request.

   • Give a descriptive title to your PR.
   • Provide a description of your changes.
   • Put closes #XXXX in your comment to auto-close the issue that your PR fixes (if such).

PLEASE REMOVE THIS TEMPLATE BEFORE SUBMITTING

[iht]

LGTM

[iht]

Thanks for this contribution to the repo!