Add `action` module.
Update `action` module and its unit tests.
Merge branch 'dev-str' into dev-action

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Update `action` module and its unit tests.
Merge pull request #10 from zpbx/dev-str

Update `str` module and its unit tests.
Merge pull request #11 from zpbx/dev-action

Add `action` module.
Merge branch 'master' into dev-dom-var

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Adapt usage in `action` module.