docs: def mktree(newdir):
      """works the way a good mkdir should :)
          - already exists, silently complete
          - regular file in the way, raise an exception
          - parent directory(ies) does not exist, make them as well
      """
      if os.path.isdir(newdir):
          pass
      elif os.path.isfile(newdir):
          raise OSError("a file with the same name as the desired "
                        "dir, '%s', already exists." % newdir)
      else:
          os.makedirs(newdir)