class junk(object):
  def __len__(self):
    return 2
  def __getitem__(self, index):
    return ["a", "b"][index]

j = junk()
print list(j)

perm = flex.sort_permutation(data=md.data())
mds = md.select(perm)
for _ in [md, mds]:
  print list(_.indices())
  print list(_.data())
  print

from cctbx import uctbx
uc = uctbx.unit_cell((3.56,3.56,5.60,90,90,120))

from cctbx import sgtbx
sgi = sgtbx.space_group_info(symbol="R3:H")