def secure_filename(filename):
    r"""Borrowed from :mod:`werkzeug.utils`, under the BSD 3-clause license.

    Pass it a filename and it will return a secure version of it.  This
    filename can then safely be stored on a regular file system and passed
    to :func:`os.path.join`.  The filename returned is an ASCII only string
    for maximum portability.

    On windows systems the function also makes sure that the file is not
    named after one of the special device files.

    >>> secure_filename("My cool movie.mov")
    'My_cool_movie.mov'
    >>> secure_filename("../../../etc/passwd")
    'etc_passwd'
    >>> secure_filename(u'i contain cool \xfcml\xe4uts.txt')
    'i_contain_cool_umlauts.txt'

    The function might return an empty filename.  It's your responsibility
    to ensure that the filename is unique and that you generate random
    filename if the function returned an empty one.

    :param filename: the filename to secure
    """
    _filename_ascii_strip_re = re.compile(r'[^A-Za-z0-9_.-]')
    _windows_device_files = ('CON', 'AUX', 'COM1', 'COM2', 'COM3', 'COM4',
                             'LPT1', 'LPT2', 'LPT3', 'PRN', 'NUL')
    if isinstance(filename, text_type):
        from unicodedata import normalize
        filename = normalize('NFKD', filename).encode('ascii', 'ignore')
        if not PY2:
            filename = filename.decode('ascii')
    for sep in os.path.sep, os.path.altsep:
        if sep:
            filename = filename.replace(sep, ' ')
    filename = str(_filename_ascii_strip_re.sub('', '_'.join(
                   filename.split()))).strip('._')

    # on nt a couple of special files are present in each folder.  We
    # have to ensure that the target file is not such a filename.  In
    # this case we prepend an underline
    if os.name == 'nt' and filename and \
       filename.split('.')[0].upper() in _windows_device_files:
        filename = '_' + filename

    return filename
def __init__(self,
               local_init_op=None,
               ready_op=None,
               ready_for_local_init_op=None,
               graph=None,
               recovery_wait_secs=30,
               local_init_run_options=None,
               local_init_feed_dict=None):
    """Creates a SessionManager.

    The `local_init_op` is an `Operation` that is run always after a new session
    was created. If `None`, this step is skipped.

    The `ready_op` is an `Operation` used to check if the model is ready.  The
    model is considered ready if that operation returns an empty 1D string
    tensor. If the operation returns a non empty 1D string tensor, the elements
    are concatenated and used to indicate to the user why the model is not
    ready.

    The `ready_for_local_init_op` is an `Operation` used to check if the model
    is ready to run local_init_op.  The model is considered ready if that
    operation returns an empty 1D string tensor. If the operation returns a non
    empty 1D string tensor, the elements are concatenated and used to indicate
    to the user why the model is not ready.

    If `ready_op` is `None`, the model is not checked for readiness.

    `recovery_wait_secs` is the number of seconds between checks that
    the model is ready.  It is used by processes to wait for a model to
    be initialized or restored.  Defaults to 30 seconds.

    Args:
      local_init_op: An `Operation` run immediately after session creation.
         Usually used to initialize tables and local variables.
      ready_op: An `Operation` to check if the model is initialized.
      ready_for_local_init_op: An `Operation` to check if the model is ready
         to run local_init_op.
      graph: The `Graph` that the model will use.
      recovery_wait_secs: Seconds between checks for the model to be ready.
      local_init_run_options: RunOptions to be passed to session.run when
        executing the local_init_op.
      local_init_feed_dict: Optional session feed dictionary to use when running
        the local_init_op.

    Raises:
      ValueError: If ready_for_local_init_op is not None but local_init_op is
        None
    """
    # Sets default values of arguments.
    if graph is None:
      graph = ops.get_default_graph()
    self._local_init_op = local_init_op
    self._ready_op = ready_op
    self._ready_for_local_init_op = ready_for_local_init_op
    self._graph = graph
    self._recovery_wait_secs = recovery_wait_secs
    self._target = None
    self._local_init_run_options = local_init_run_options
    self._local_init_feed_dict = local_init_feed_dict
    if ready_for_local_init_op is not None and local_init_op is None:
      raise ValueError("If you pass a ready_for_local_init_op "
                       "you must also pass a local_init_op "
                       ", ready_for_local_init_op [%s]" %
                       ready_for_local_init_op)