docs: def sort_func(variant=VARIANT1, case_sensitive=False):
      """A function generator that can be used for sorting.
  
      All keywords are passed to `normalize()` and generate keywords that
      can be passed to `sorted()`::
  
        >>> key = sort_func()
        >>> print(sorted(["fur", "far"], key=key))
        [u'far', u'fur']
  
      Please note, that `sort_func` returns a function.
      """
      return lambda x: normalize(
          x, variant=variant, case_sensitive=case_sensitive)