docs: def finalise_same_chip_constraints(substitutions, placements):
      """Given a set of placements containing the supplied
      :py:class:`MergedVertex`, remove the merged vertices replacing them with
      their constituent vertices (changing the placements inplace).
      """
      for merged_vertex in reversed(substitutions):
          placement = placements.pop(merged_vertex)
          for v in merged_vertex.vertices:
              placements[v] = placement