Fix about_open_classes koan

[#5414569]
Fix about_dice_project koan

[#54145695]
Fix about_modules koan

[#54145699]
Merge pull request #26 from bayendor/54145699_about_modules_master

Fix about_modules koan

[Delivers #54145699]
Merge pull request #25 from bayendor/54145697_about_inheritance_master

Fix about_inheritance koan

[Delivers #54145697]
Merge pull request #23 from bayendor/5414569_about_open_classes_master

Fix about_open_classes koan

[Delivers #5414569]
Merge pull request #24 from bayendor/54145695_about_dice_project_master

Fix about_dice_project koan

[Delivers #54145695]