def download_file(url, dest=None, chunk_size=1024, replace="ask",
                  label="Downloading {dest_basename} ({size:.2f}MB)",
                  expected_extension=None):
    """Download a file from a given URL and display progress.

    :param dest: If the destination exists and is a directory, the filename
        will be guessed from the Content-Disposition header. If the destination
        is an existing file, the user will either be prompted to overwrite, or
        the file will be replaced (depending on the value of **replace**). If
        the destination does not exist, it will be used as the filename.
    :param int chunk_size: bytes read in at a time.
    :param replace: If `False`, an existing destination file will not be
        overwritten.
    :param label: a string which is formatted and displayed as the progress bar
        label. Variables provided include *dest_basename*, *dest*, and *size*.
    :param expected_extension: if set, the filename will be sanitized to ensure
        it has the given extension. The extension should not start with a dot
        (`.`).
    """
    dest = Path(dest or url.split("/")[-1])
    response = get(url, stream=True)
    if (dest.exists()
            and dest.is_dir()
            and "Content-Disposition" in response.headers):
        content_disposition = rfc6266.parse_requests_response(response)
        if expected_extension is not None:
            filename = content_disposition.filename_sanitized(
                expected_extension)
        filename = secure_filename(filename)
        dest = dest / filename
    if dest.exists() and not dest.is_dir():
        if (replace is False
                or replace == "ask"
                and not click.confirm("Replace {}?".format(dest))):
            return str(dest)
    size = int(response.headers.get("content-length", 0))
    label = label.format(dest=dest, dest_basename=dest.name,
                         size=size/1024.0/1024)
    with click.open_file(str(dest), "wb") as f:
        content_iter = response.iter_content(chunk_size=chunk_size)
        with click.progressbar(content_iter, length=size/1024,
                               label=label) as bar:
            for chunk in bar:
                if chunk:
                    f.write(chunk)
                    f.flush()
    return str(dest)
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)