DOC: Fix syntax error in groupby docs

[gfyoung]

https://travis-ci.org/pandas-dev/pandas/jobs/450582832

#15559 has been rearing its head again. Turns out the reason for the timeout is one silly, missing parenthesis in the groupby.rst docs (that was the cause as well in #15506). 😆

Follow-up to #23394.

[jreback]

maybe make this actually do something? e.g .sum() to show the resulting frame

[gfyoung]

maybe make this actually do something? e.g .sum() to show the resulting frame

@jreback : That's fair. I do want to make sure that the Travis build first doesn't timeout. Then we can add something to show the result.

[codecov]

Codecov Report

Merging #23498 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #23498   +/-   ##
=======================================
  Coverage   92.23%   92.23%           
=======================================
  Files         161      161           
  Lines       51197    51197           
=======================================
  Hits        47220    47220           
  Misses       3977     3977

Flag	Coverage Δ
#multiple	90.61% <ø> (ø)	⬆️
#single	42.27% <ø> (ø)	⬆️

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[datapythonista]

lgtm

[gfyoung]

@jreback : Made the suggested change, and all builds (including the doc build) are green. PTAL.

[jorisvandenbossche]

@gfyoung Thanks for finding the trigger for the doc time out! Luckily it was something very simple in the end ;) (I still don't understand how this caused such a slow down without giving actual errors)

(but maybe in the future if you are re-doing a PR that broke the doc build, make sure to check if now the doc build is actually working .. :))

[gfyoung]

(but maybe in the future if you are re-doing a PR that broke the doc build, make sure to check if now the doc build is actually working .. :))

@jorisvandenbossche : The doc builds were working in fact when I first opened the PR. It was a mysterious bug that reared its head in strange ways. 🙂

[jorisvandenbossche]

@gfyoung yeah, I can only see the status of the last commit (in general, can you start adding new commits instead of rebasing/amending a single commit in a PR ?), and there it was actually failing, although it looks green. I think we discussed that before, but we should probably move the doc build out of "allowed failures".