* add GCN sparse matrix example
* refine GCN example
* refine GCN example
* change train function
* [Bugfix] Turn off `use_alternate_stream` when TensorAdaptor is not enabled (#4987)
* turn off use_alternate_stream when tensoradaptor is not enabled
* add docstring
* Update (#4997)
Co-authored-by: Ubuntu <ubuntu@ip-172-31-36-188.ap-northeast-1.compute.internal>
* refine GCN example
* add GCN sparse matrix example
* refine GCN example
* refine GCN example
* change train function
* refine GCN example
* add highlight comment
* refine code
* refine code
* refine by black and flake8
* refine the comment to 80 char length
* refine the comment
* refine comment
Co-authored-by: Xin Yao <xiny@nvidia.com>
Co-authored-by: Mufei Li <mufeili1996@gmail.com>
Co-authored-by: Ubuntu <ubuntu@ip-172-31-36-188.ap-northeast-1.compute.internal>