close #26, changed categorisation strategie according to comment

[DariaPigasova]

Related issue(s)

Quality assurance tasks

• General
  • [x] An issue exists to this pull request
  • [x] Reviewer were set (mostly this will be Emma developers)
  • [x] Assignee is set (you)
  • [ ] ~Related commits have been squashed~
  • [x] PyLint results have been checked and issues resolved
  • [ ] ~Emma version updated~
• Testing
  • [ ] ~Unit/functional tests have been added/updated~
  • [x] Manual testing in real environment has been performed and documented
• Documentation
  • [x] Documentation has been added/updated
  • [x] Breaking changes have been documented and tagged in commit message
  • [x] Related issues have been tagged (-> #45 for issue 45) in the commit message(s) => tip: use references