[Pharo-users] Modify AST to send a message on Character nodes

Hi everyone, I would like to modify the AST of a smalltalk expression compiled to automatically send a certain message when a node represents a Character (so the user does not have to write the message sending explicitly). I would of course add a special button in the menu you get when right clicking in a playground so the user knows it is a "special" do-it... For example: $a. would transform into an ast that the source code looks like $a aMessage How can I do this? :) Julien