Simplices for element references

[scdivi]

Recent nutils updates breaks our immersed scripts (for example: potential-flow and img2mesh). This is mainly related to simplices of an element reference. It doesn't return transforms and references for TensorReference and not implemented/removed for WithChildrenReference. Is it introduced in a different form? If so, do you have an alternative for the following snippet?

def get_fragment_topo(self):
  references = []
  transforms = []
  opposites  = []
  for elemrefs, elemtrans, elemopp in zip(self.references,self.transforms, self.opposites):
    for trans, refs in elemrefs.simplices:
      references.append(refs)
      transforms.append(elemtrans+(trans,))
      opposites.append(elemopp+(trans,))
  references = elementseq.References.from_iter(references, self.ndims)
  opposites  = transformseq.PlainTransforms(opposites , fromdims=self.ndims, todims=self.ndims)
  transforms = transformseq.PlainTransforms(transforms, fromdims=self.ndims, todims=self.ndims)
  # spaces of the topology
  space, = self.spaces
  return topology.TransformChainsTopology(space, references, transforms, opposites)