2. fix test_graphdata_distributed.py failing randomly

implment pause in MapOp, added more to callback

add ds_callback

- Initial drop of Python DSCallback

- Pybind DSCallback

- Pybind DSCallback

added callback to mapOp

- de_pipeline DSCallback

- de_pipeline DSCallback

add test case, segfault for now

fix seg fault

- de_pipeline DSCallback

remove 1 line

update callback test case, now works

use builder class for mapOp callback

- de_pipeline DSCallback

- de_pipeline DSCallback

- de_pipeline DSCallback

better test case

minor fix

add comments and minor clean ups

get rid of nullptr in MapOp, use other flag instead

fix a bug ParseMapOp only takes 1 callback

- Added WaitedDSCalabck

refactor callback param

fix text case incorrect number

- added testing

fix cpp test case

- added testing

- revert back lenet changes

- cleanup test_callbacks.py

- cleanup test_callbacks.py

fix CI stage I

fix CI stage II

fix CI and update epoch counter

- add validation
- add more testing  test_callbacks.py

use random data op to do tests

adjust when to call EpochBegin/End

- add repeat with callback

- addressing reviewers' comments

- docstring and CI fixes

- docstring and CI fixes

- docstring and CI fixes

- rebase with upstream/master

fix cpp test case

fix review comments

addr review cmts, add test case

Merge pull request !4383 from genglishuai/genglshOK

Merge pull request !3651 from jiangzhiwen/dataset/change_num_samples

Add parameter verification

Merge pull request !2934 from heleiwang/gnn_july

fixed random_apply tests

fix validators

fixed random_apply tests

fix engine validation

add fix to random resize decode crop test case

fix pylint issues

Merge pull request !2380 from xiefangqi/xfq_fix_coco_issue_01

init remove storage op test case c++

remove source c++ files

Merge pull request !2189 from ms_yan/numpy_slice_repair

Merge pull request !1977 from JonathanY/randomwalk

Merge pull request !2145 from cathwong/ckw_dataset_npsum_slice_warn

c implementation done, just need to call batch/pad

added python api and validator

added pybind/de_pipeline stuff, fixed some compile errors, figure out how null py::function works

added tiny bit of doc

integrated with static batch methods

fixed some bugs

some more bug fixes and cleanup

ci fix

fix ci

ci fix

fix ci

added test_cases and debugged

addressed code review comments

addressed code review comments

ci fix

ci fix

addressed code review comments

addressed code review comments

Merge pull request !1913 from xiefangqi/xfq_support_coco

2. mod cora and citeseer conversion script

Merge pull request !1874 from h.farahat/string_tensor_updates

- Support accepting Numpy of str as input
- Support batching strings
- Core logic of batch&pad is static
- Make Pad a utility function