TypeError: 'numpy.float64' object cannot be interpreted as an index

[SeekPoint]

python tasks/copy/train.py --iterations=50000
Building Computational Graph ... Traceback (most recent call last):
File "tasks/copy/train.py", line 82, in
batch_size
File "/Users/yike.ke/yike_prj/DNC-tensorflow/tasks/copy/dnc/dnc.py", line 46, in init
self.controller = controller_class(self.input_size, self.output_size, self.read_heads, self.word_size, self.batch_size)
File "/Users/yike.ke/yike_prj/DNC-tensorflow/tasks/copy/dnc/controller.py", line 45, in init
self.network_vars()
File "/Users/yike.ke/yike_prj/DNC-tensorflow/tasks/copy/feedforward_controller.py", line 16, in network_vars
self.W1 = tf.Variable(tf.truncated_normal([input_, 128], stddev=initial_std(input_)), name='layer1_W')
File "/Users/yike.ke/yike_prj/DNC-tensorflow/tasks/copy/feedforward_controller.py", line 13, in
initial_std = lambda in_nodes: np.min(1e-2, np.sqrt(2.0 / in_nodes))
File "/Users/yike.ke/yike_prj/ve_tf0.11_py2/venv/lib/python2.7/site-packages/numpy/core/fromnumeric.py", line 2372, in amin
out=out, **kwargs)
File "/Users/yike.ke/yike_prj/ve_tf0.11_py2/venv/lib/python2.7/site-packages/numpy/core/_methods.py", line 29, in _amin
return umr_minimum(a, axis, None, out, keepdims)
TypeError: 'numpy.float64' object cannot be interpreted as an index