old_contents: from .utils import import_helpers
  
  __name__ = 'plasmapy'
  
  __doc__ = ('A community-developed and community-driven open source core '
             'Python package for plasma physics.')
  
  try:
      from .version import version as __version__
  except ImportError:
      __version__ = ''
  
  __minimum_python_version__ = '3.6'
  
  __minimum_versions__ = {
      'numpy': '1.13',
      'astropy': '2.0',
      }
  
  import_helpers.check_python(__minimum_python_version__)
  import_helpers.check_versions(__minimum_versions__)
  
  try:
      from .classes import Plasma
      from . import classes
      from . import constants
      from . import atomic
      from . import mathematics
      from . import physics
      from . import utils
  except ImportError as exc:
      raise ImportError('Unable to load PlasmaPy subpackages.') from exc
  
  # Clean up the top-level namespace by deleting everything that (1)
  # isn't listed in keep, (2) is a dunder, and (3) isn't a submodule of
  # this package.  This was adapted from astropy's __init__.py.
  
  __keep__ = ['Plasma']
  
  from types import ModuleType as __module_type__
  
  for varname in dir():
  
      in_keep = varname in __keep__
  
      is_dunder = varname.startswith('__') and varname.endswith('__')
  
      # When using relative imports like ``from .. import config``, the
      # ``config`` variable is automatically created in the namespace of
      # whatever module ``..`` resolves to (in this case astropy).  This
      # happens a few times just in the module setup above.  This allows
      # the cleanup to keep any public submodules of the package.
  
      is_subpackage = (varname[0] != '_' and
                       isinstance(locals()[varname], __module_type__) and
                       locals()[varname].__name__.startswith(__name__ + '.'))
  
      if not (in_keep or is_dunder or is_subpackage):
          del locals()[varname]
  
  del (import_helpers, __minimum_python_version__, __minimum_versions__,
       varname, __module_type__, __keep__, in_keep, is_dunder, is_subpackage)
  
new_contents: from .utils import import_helpers
  
  __name__ = 'plasmapy'
  
  __doc__ = ('A community-developed and community-driven open source core '
             'Python package for plasma physics.')
  
  try:
      from .version import version as __version__
  except ImportError:
      __version__ = '0.1.0dev0'
  
  __minimum_python_version__ = '3.6'
  
  # The following information is duplicated in requirements/base.txt
  
  __minimum_versions__ = {
      'numpy': '1.13',
      'astropy': '2.0',
      'scipy': '0.19',
      }
  
  import_helpers.check_python(__minimum_python_version__)
  import_helpers.check_versions(__minimum_versions__)
  
  try:
      from .classes import Plasma
      from . import classes
      from . import constants
      from . import atomic
      from . import mathematics
      from . import physics
      from . import utils
  except ImportError as exc:
      raise ImportError('Unable to load PlasmaPy subpackages.') from exc
  
  # A more extensive and thoughtful method for cleaning up our top-level
  # namespace is in Astropy's __init__.py (see also pull request #210).
  
  del (import_helpers, __minimum_python_version__, __minimum_versions__)
  
subject: Remove loop for cleaning up top-level namespace