id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
513068398,MDExOlB1bGxSZXF1ZXN0MzMyOTI3ODIy,3453,Optimize dask array equality checks.,2448579,closed,0,,,3,2019-10-28T02:44:14Z,2019-11-05T15:41:22Z,2019-11-05T15:41:15Z,MEMBER,,0,pydata/xarray/pulls/3453,"Dask arrays with the same graph have the same name. We can use this to quickly
compare dask-backed variables without computing. (see https://github.com/pydata/xarray/issues/3068#issuecomment-508853564)

I will work on adding extra tests but could use feedback on the approach.

<!-- Feel free to remove check-list items aren't relevant to your change -->

 - [x] Closes #3068, closes #3311, closes #3454 
 - [x] Tests added
 - [x] Passes `black . && mypy . && flake8`
 - [x] Fully documented, including `whats-new.rst` for all changes and `api.rst` for new API

@djhoese, thanks for the great example code!
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