GitLab

* update agg function with new bindings

* handle optional import in __init__

* raise error in RelGraphConvAgg when pylibcugraphops not imported

* Update tests/cugraph/cugraph-ops/test_cugraph_relgraphconv.py
Co-authored-by: Mufei Li <mufeili1996@gmail.com>

* Update tests/cugraph/cugraph-ops/test_cugraph_relgraphconv.py
Co-authored-by: Mufei Li <mufeili1996@gmail.com>

* use keyword args for readability

* add missing docstring to pass CI

* catch ImportError rather than ModuleNotFoundError
Co-authored-by: Mufei Li <mufeili1996@gmail.com>