indexed objects like (a+b).i -> a.i + b.i
* Renamed get_indices() to get_free_indices(), which no longer returns
dummy indices and checks the consistency of indices in sums.
indexed objects like (a+b).i -> a.i + b.i
* Renamed get_indices() to get_free_indices(), which no longer returns
dummy indices and checks the consistency of indices in sums.