Tracer

[huancui]

If you haven't already, please review our contributing guidelines before opening your pull request.

Use this template to give a detailed message describing the change you want to make to the code.

The title of this pull request should be a brief "purpose" for this change.

--- Delete this line and those above before hitting "Create pull request" ---

TYPE: choose one of [bug fix, enhancement, new feature, feature removed, no impact, text only]

KEYWORDS: approximately 3 to 6 words (more is always better) related to your commit, separated by commas

SOURCE: Developer's name and affiliation

DESCRIPTION OF CHANGES: One or more paragraphs describing problem, solution, and required changes.

ISSUE: The GitHub Issue that this PR addresses. For issue number 123, it would be:

Fixes #123

TESTS CONDUCTED: Explicitly state if regression, integration, or unit tests were run before submitting (do not include the CI tests automatically run by GitHub)

NOTES: Optional, as appropriate. Delete if not used. Included only once for new features requiring several merge cycles. Changes to default behavior are also note worthy.

Checklist

Merging the PR depends on following checklist being completed. Add X between each of the square brackets if they are completed in the PR itself. If a bullet is not relevant to you, please comment on why below the bullet.

• [ ] Closes issue #xxxx (An issue must exist or be created to be closed. The issue describes and documents the problem and general solution, the PR describes the technical details of the solution.)
• [ ] Tests added (unit tests and/or regression/integration tests)
• [ ] Backwards compatible
• [ ] Requires new files? If so, how to generate them.
• [ ] Documentation included
• [ ] Short description in the Development section of NEWS.md

[scrasmussen]

@huancui If you could please edit the first comment, which is the pull request template for your pull request, that would help us start to be able to process it. Additionally, there are a number of merge conflicts that will need to be resolved before the CI tests can be run on them. If you have questions feel free to ask them, thanks!