The former `PrefixSum` class was renamed to `Scan`, but the methods in vector classes (`Vector`, `VectorView`, `DistributedVector` and `DistributedVectorView`) stayed as `prefixSum` and `segmentedPrefixSum` - see e.g. https://mmg-gitlab.fjfi.cvut.cz/gitlab/tnl/tnl-dev/blob/develop/src/TNL/Containers/Vector.h#L269 While we're renaming things, `exclusiveScan` method should be added as a shortcut for `vector.template scan< TNL::Containers::Algorithms::ScanType::Exclusive >()`. Both methods should be used in the [tutorial](https://mmg-gitlab.fjfi.cvut.cz/doc/tnl/tutorial_03_reduction.html#flexible_scan).