old_contents: #! python
  from __future__ import print_function, division  # Require Python 2.6 or later
  from . import constants
  from . import Bohr
  from .Ps import Ps
new_contents: #! python
  from __future__ import print_function, division  # Require Python 2.6 or later
  from . import constants
  from . import Bohr
  #from .Ps import Ps
subject: remove imprt of test module