fixing bug in discover_modules, thanks to @Vanuan for finding it. Resolves what's left of #1
extracting function for better testability
this behaviour needs a test.. The .py is stripped because we're dealing with modules, not because the suffix happends to be .py by default... so module[0:-3] is not the suffix being hardcoded but rather always the python source file ending......
trying to make this a bit clearer by renaming the variable as its contents change