text: import sys
  from lib2to3 import refactor
  
  # The following fixers are "safe": they convert Python 2 code to more
  # modern Python 2 code. They should be uncontroversial to apply to most
  # projects that are happy to drop support for Py2.5 and below. Applying
  # them first will reduce the size of the patch set for the real porting.
  lib2to3_fix_names_stage1 = set([
      'lib2to3.fixes.fix_apply',
      'lib2to3.fixes.fix_except',
      'lib2to3.fixes.fix_exec',
      'lib2to3.fixes.fix_exitfunc',
      'lib2to3.fixes.fix_funcattrs',
      'lib2to3.fixes.fix_has_key',
      'lib2to3.fixes.fix_idioms',
      # 'lib2to3.fixes.fix_import',    # makes any implicit relative imports explicit. (Use with ``from __future__ import absolute_import)
      'lib2to3.fixes.fix_intern',
      'lib2to3.fixes.fix_isinstance',
      'lib2to3.fixes.fix_methodattrs',
      'lib2to3.fixes.fix_ne',
      # 'lib2to3.fixes.fix_next',         # would replace ``next`` method names
                                          # with ``__next__``.
      'lib2to3.fixes.fix_numliterals',    # turns 1L into 1, 0755 into 0o755
      'lib2to3.fixes.fix_paren',
      # 'lib2to3.fixes.fix_print',        # see the libfuturize fixer that also
                                          # adds ``from __future__ import print_function``
      # 'lib2to3.fixes.fix_raise',   # uses incompatible with_traceback() method on exceptions
      'lib2to3.fixes.fix_reduce',    # reduce is available in functools on Py2.6/Py2.7
      'lib2to3.fixes.fix_renames',        # sys.maxint -> sys.maxsize
      # 'lib2to3.fixes.fix_set_literal',  # this is unnecessary and breaks Py2.6 support
      'lib2to3.fixes.fix_repr',
      'lib2to3.fixes.fix_standarderror',
      'lib2to3.fixes.fix_sys_exc',
      'lib2to3.fixes.fix_throw',
      'lib2to3.fixes.fix_tuple_params',
      'lib2to3.fixes.fix_types',
      'lib2to3.fixes.fix_ws_comma',       # can perhaps decrease readability: see issue #58
      'lib2to3.fixes.fix_xreadlines',
  ])
  
  # The following fixers add a dependency on the ``future`` package on order to
  # support Python 2:
  lib2to3_fix_names_stage2 = set([
      # 'lib2to3.fixes.fix_buffer',    # perhaps not safe. Test this.
      # 'lib2to3.fixes.fix_callable',  # not needed in Py3.2+
      'lib2to3.fixes.fix_dict',        # TODO: add support for utils.viewitems() etc. and move to stage2
      # 'lib2to3.fixes.fix_execfile',  # some problems: see issue #37.
                                       # We use a custom fixer instead (see below)
      # 'lib2to3.fixes.fix_future',    # we don't want to remove __future__ imports
      'lib2to3.fixes.fix_getcwdu',
      # 'lib2to3.fixes.fix_imports',   # called by libfuturize.fixes.fix_future_standard_library
      # 'lib2to3.fixes.fix_imports2',  # we don't handle this yet (dbm)
      'lib2to3.fixes.fix_input',
      'lib2to3.fixes.fix_itertools',
      'lib2to3.fixes.fix_itertools_imports',
      'lib2to3.fixes.fix_filter',
      'lib2to3.fixes.fix_long',
      'lib2to3.fixes.fix_map',
      # 'lib2to3.fixes.fix_metaclass', # causes SyntaxError in Py2! Use the one from ``six`` instead
      'lib2to3.fixes.fix_next',
      'lib2to3.fixes.fix_nonzero',     # TODO: cause this to import ``object`` and/or add a decorator for mapping __bool__ to __nonzero__
      'lib2to3.fixes.fix_operator',    # we will need support for this by e.g. extending the Py2 operator module to provide those functions in Py3
      'lib2to3.fixes.fix_raw_input',
      # 'lib2to3.fixes.fix_unicode',   # strips off the u'' prefix, which removes a potentially helpful source of information for disambiguating unicode/byte strings
      # 'lib2to3.fixes.fix_urllib',    # included in libfuturize.fix_future_standard_library_urllib
      # 'lib2to3.fixes.fix_xrange',    # custom one because of a bug with Py3.3's lib2to3
      'lib2to3.fixes.fix_zip',
  ])
  
  libfuturize_fix_names_stage1 = set([
      'libfuturize.fixes.fix_absolute_import',
      'libfuturize.fixes.fix_next_call',  # obj.next() -> next(obj). Unlike
                                          # lib2to3.fixes.fix_next, doesn't change
                                          # the ``next`` method to ``__next__``.
      'libfuturize.fixes.fix_print_with_import',
      'libfuturize.fixes.fix_raise',
      # 'libfuturize.fixes.fix_order___future__imports',  # TODO: consolidate to a single line to simplify testing
  ])
  
  libfuturize_fix_names_stage2 = set([
      'libfuturize.fixes.fix_basestring',
      # 'libfuturize.fixes.fix_add__future__imports_except_unicode_literals',  # just in case
      'libfuturize.fixes.fix_cmp',
      'libfuturize.fixes.fix_division_safe',
      'libfuturize.fixes.fix_execfile',
      'libfuturize.fixes.fix_future_builtins',
      'libfuturize.fixes.fix_future_standard_library',
      'libfuturize.fixes.fix_future_standard_library_urllib',
      'libfuturize.fixes.fix_metaclass',
      'libpasteurize.fixes.fix_newstyle',
      'libfuturize.fixes.fix_object',
      # 'libfuturize.fixes.fix_order___future__imports',  # TODO: consolidate to a single line to simplify testing
      'libfuturize.fixes.fix_unicode_keep_u',
      # 'libfuturize.fixes.fix_unicode_literals_import',
      'libfuturize.fixes.fix_xrange_with_import',  # custom one because of a bug with Py3.3's lib2to3
  ])
  