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                        Add BranchingSum MVB branching environment
Pull request checklist
- [x] I have opened an issue to discuss the proposed changes: Fix #158
- [x] I have modified/added tests to cover the new changes/features.
- [x] I have modified/added the documentation to cover the new changes/features.
- [x] I have ran the tests, checks, and code formatters.
Proposed implementation
This are the change that were removed in #298. This PR is faulty and needs further investigation.