code: def commit_changeset(self, changeset_id: uuid.UUID) -> Dict[bytes, Union[bytes, DeletedEntry]]:
          
          does_clear = self.has_clear(changeset_id)
          changeset_data = self.pop_changeset(changeset_id)
          if not self.is_empty():
              # we only have to assign changeset data into the latest changeset if
              # there is one.
              if does_clear:
                  # if there was a clear and more changesets underneath then clear the latest
                  # changeset, and replace with a new clear changeset
                  self.latest = {}
                  self._clears_at.add(self.latest_id)
                  self.record_changeset()
                  self.latest = changeset_data
              else:
                  # otherwise, merge in all the current data
                  self.latest = merge(
                      self.latest,
                      changeset_data,
                  )
          return changeset_data
docs: Collapses all changes for the given changeset into the previous
          changesets if it exists.