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,
               resnet_size,
               bottleneck,
               num_classes,
               num_filters,
               kernel_size,
               conv_stride,
               first_pool_size,
               first_pool_stride,
               block_sizes,
               block_strides,
               resnet_version=DEFAULT_VERSION,
               data_format=None,
               dtype=DEFAULT_DTYPE):
    """Creates a model for classifying an image.

    Args:
      resnet_size: A single integer for the size of the ResNet model.
      bottleneck: Use regular blocks or bottleneck blocks.
      num_classes: The number of classes used as labels.
      num_filters: The number of filters to use for the first block layer of the
        model. This number is then doubled for each subsequent block layer.
      kernel_size: The kernel size to use for convolution.
      conv_stride: stride size for the initial convolutional layer
      first_pool_size: Pool size to be used for the first pooling layer. If
        none, the first pooling layer is skipped.
      first_pool_stride: stride size for the first pooling layer. Not used if
        first_pool_size is None.
      block_sizes: A list containing n values, where n is the number of sets of
        block layers desired. Each value should be the number of blocks in the
        i-th set.
      block_strides: List of integers representing the desired stride size for
        each of the sets of block layers. Should be same length as block_sizes.
      resnet_version: Integer representing which version of the ResNet network
        to use. See README for details. Valid values: [1, 2]
      data_format: Input format ('channels_last', 'channels_first', or None). If
        set to None, the format is dependent on whether a GPU is available.
      dtype: The TensorFlow dtype to use for calculations. If not specified
        tf.float32 is used.

    Raises:
      ValueError: if invalid version is selected.
    """
    self.resnet_size = resnet_size

    if not data_format:
      data_format = ('channels_first'
                     if tf.test.is_built_with_cuda() else 'channels_last')

    self.resnet_version = resnet_version
    if resnet_version not in (1, 2):
      raise ValueError(
          'Resnet version should be 1 or 2. See README for citations.')

    self.bottleneck = bottleneck
    self.block_fn = _building_block_v2

    if dtype not in ALLOWED_TYPES:
      raise ValueError('dtype must be one of: {}'.format(ALLOWED_TYPES))

    self.data_format = data_format
    self.num_classes = num_classes
    self.num_filters = num_filters
    self.kernel_size = kernel_size
    self.conv_stride = conv_stride
    self.first_pool_size = first_pool_size
    self.first_pool_stride = first_pool_stride
    self.block_sizes = block_sizes
    self.block_strides = block_strides
    self.dtype = dtype
    self.pre_activation = resnet_version == 2