I downloaded this mod but it does nothing. How do I run it?
You need to run it from a terminal / command prompt. It requires a recent version of python available from www.python.org. I recommend the 64 bit version.

Why is it a mod?
Easier distribution. Its a Factorio tool so its easier for people who know Factorio to get it as a mod.

Why can't Factorio run it?
Factorio has an embedded lua interpreter but it can't read/write files. So I took a similar tool I wrote in a very different language and I've converted its ideas to Python.

Why python?
Slower than lua but more readable by others. String handling is built-in with few horrible quirks.

Where's the docs?
Not written yet. The tool is basically self explanatory for those knowing what a mod is. The source is there for those who understand python.

What platforms does it run on?
Windows 10, Linux (debian) and mac are all confirmed. I develop on all three so a "primary" doesn't actually mean anything.

Errors, Warnings, Information?
Errors are things that you should definitely fix. This includes things that cause Factorio to complain.
Warnings are things that will trip you up if you ignore them. This includes things that you meant to do but probably didn't.
Information is the tool raising your attention to something that might annoy, frustrate or otherwise cause an unpleasant surprise if you otherwise didn't know about it.
You can likely ignore all messages (!) but the results might not be helpful.

Whats the --mods-folder option for?
Likely scenario: You have a collection of mods and you want to check all of them. They are all under a single folder.

Whats the --changelog / -f option for?
You have a single file you want to check.

I tried specifying multiple changelogs but it errorred. Why?
--changelog x --changelog y
put the switch before each filepath.

The tool is wrong! What now?
It happens. Give me an example changelog.txt and attach it to a discussion message. Explain the line number and what should have happened. Provide the tool's output. Provide the version of the tool you are using.