How to create code action?

Stream: general

[Asei Inoue]

I want to understand how to create code action.

For example, is it possible to write a code action that convert #eval A = B to #guard A = B when A = B is true?

[Aaron Liu]

that should be possible

[Asei Inoue]

How to achieve this?

[Aaron Liu]

I know of docs#Lean.Elab.Tactic.GuardMsgs.guardMsgsCodeAction you can use that as an example