Traceback (most recent call last):
  File "3.py", line 52, in <module>
    heatmap = visualize_saliency(model, layer_idx, [pred_class], x)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/keras_vis-0.3.1-py2.7.egg/vis/visualization.py", line 150, in visualize_saliency
    opt = Optimizer(model.input, losses, norm_grads=False)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/keras_vis-0.3.1-py2.7.egg/vis/optimizer.py", line 35, in __init__
    loss_fn = weight * loss.build_loss()
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/keras_vis-0.3.1-py2.7.egg/vis/losses.py", line 84, in build_loss
    loss += -K.mean(layer_output[:, idx])
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/ops/array_ops.py", line 497, in _SliceHelper
    name=name)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/ops/array_ops.py", line 655, in strided_slice
    shrink_axis_mask=shrink_axis_mask)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/ops/gen_array_ops.py", line 3568, in strided_slice
    shrink_axis_mask=shrink_axis_mask, name=name)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/framework/op_def_library.py", line 768, in apply_op
    op_def=op_def)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 2338, in create_op
    set_shapes_for_outputs(ret)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 1719, in set_shapes_for_outputs
    shapes = shape_func(op)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/framework/ops.py", line 1669, in call_with_requiring
    return call_cpp_shape_fn(op, require_shape_fn=True)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/framework/common_shapes.py", line 610, in call_cpp_shape_fn
    debug_python_shape_fn, require_shape_fn)
  File "/Users/zhishanzhang/code/ke2/lib/python2.7/site-packages/tensorflow/python/framework/common_shapes.py", line 676, in _call_cpp_shape_fn_impl
    raise ValueError(err.message)
ValueError: slice index 1 of dimension 1 out of bounds. for 'strided_slice_1' (op: 'StridedSlice') with input shapes: [?,1], [2], [2], [2] and with computed input tensors: input[1] = <0 1>, input[2] = <0 2>, input[3] = <1 1>.