Description

According to Clara users' feedback and FAQs about handlers, this PR enhanced the doc-strings of all the batch_transform and output_transform args of handlers to explicitly indicate what this callable will get and from where and be used for what.
Also fixed some wrong doc-string and added missing doc-string.

Status

Ready

Types of changes

• Non-breaking change (fix or new feature that would not break existing functionality).
• Breaking change (fix or new feature that would cause existing functionality to change).
• New tests added to cover the changes.
• Integration tests passed locally by running ./runtests.sh -f -u --net --coverage.
• Quick tests passed locally by running ./runtests.sh --quick --unittests.
• In-line docstrings updated.
• Documentation updated, tested make html command in the docs/ folder.