Add TaskResult.foldResult

[Maxumka]

Proposed Changes

resolve #218

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

• Build and tests pass locally
• I have added tests that prove my fix is effective or that my feature works (if appropriate)
• I have added necessary documentation (if appropriate)

[TheAngryByrd]

Thank you!

Note: I realized we weren't running tests in CI so I had to rebase your branch after I fixed it and force push.