Give them the same return type as `erl_lint:format_error/1`.
Otherwise Rebar cannot handle henshin as a dependency :(
This parse transform checks whether any module in a remote function call is an henshin module and apply any transformation rule found to the given AST. A warning is issued if a module cannot be find at compile-time. Care is taken to handle errors gracefully. When a rule is applied, its result is transformed so that any introduced rule call is also transformed.
For the time being, rules transformation and rules application will be in two separate parse transforms.