This language feature would massively help with Proposal to Adopt the Namespaced Interfaces Pattern as a Best Practice for IC Developers. Right now a bunch of logic needs to be duplicated to support legacy interfaces and the ability to abstract code into lazy private functions would fix that. Would queries be able to call lazy functions? See the pull request on the 5th post to see how annoying this is if you want two exposed functions to call these same code or have the same query at two endpoints.