ScalableGCN运行命令

采用的cora数据集，已经按成功按官网转成了二进制形式，运行命令：
python -m tf_euler --data_dir cora --max_id 2707 --model scalable_gcn --mode train --num_classes 5

下面是运行错误：File "/usr/local/lib/python2.7/dist-packages/euler_gl-0.1.2-py2.7.egg/tf_euler/python/encoders.py", line 157, in call
embedding = tf.concat(embeddings, -1)
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/ops/array_ops.py", line 1124, in concat
return gen_array_ops.concat_v2(values=values, axis=axis, name=name)
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/ops/gen_array_ops.py", line 1033, in concat_v2
"ConcatV2", values=values, axis=axis, name=name)
File "/usr/local/lib/python2.7/dist-packages/tensorflow/python/framework/op_def_library.py", line 570, in _apply_op_helper
(input_name, op_type_name, len(values), num_attr.minimum))
ValueError: List argument 'values' to 'ConcatV2' Op with length 0 shorter than minimum length 2.

请问：运行命令中还要加什么吗？

Reproduce the reported command with the converted cora dataset, then inspect tf_euler/python/encoders.py at line 157 where tf.concat receives an empty list. Trace why no embeddings are produced and verify the needed command or configuration by rerunning training without the ConcatV2 error.

Written by the indexing model from the issue text.