I think you could safely just change the method signature to something like: `Conditional.not_if(parent_resource, command, opts, &block)` or do the ugly backcompat thing like: `Conditional.not_if_with_guard_interpreter_support(parent_resource, command, opts, &block)`

In either case, the `Conditional` object would then be responsible for handling guard interpreter stuff, which seems like a better place for that logic to me.