[function] Add a built-in function

[qinkunbao]

Description

Add a built-in function.

Fixes # (issue)

Type of change (select or add applied and delete the others)

• Bug fix (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)
• API change with a documentation update
• Additional test coverage
• Code cleanup or just sync with upstream third-party crates

How has this been tested?

Checklist

• Fork the repo and create your branch from master.
• If you've added code that should be tested, add tests.
• If you've changed APIs, update the documentation.
• Ensure the tests pass (see CI results).
• Make sure your code lints/format.

[mssun]

Thanks.

You can add this example in the test by adding it here:

incubator-teaclave/cmake/scripts/test.sh

Line 160 in 51e7ee8

python3 ${TEACLAVE_PROJECT_ROOT}/examples/python/mesapy_echo.py

Then run make run-examples to test all examples.

[qinkunbao]

OK, I added this example and all tests passed.

[mssun]

Please use make format to format all rust code.

[qinkunbao]

Thank you for the feedback. All requested changes are addressed now.

[mssun]

LGTM.

I'm building/testing the code. Will merge it if passed. Thanks!

[mssun]

Merged. Thanks.