DOC: Fixing more doc warings and wrong .. code-block :: directive (space before colon)

[datapythonista]

Using .. code-block :: with a space before the colon wasn't making the blocks be validated for flake8 issues. Same for ipython directive.

Making sure the space is not present, and fixing flake8 errors.

[codecov]

Codecov Report

Merging #24650 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #24650      +/-   ##
==========================================
+ Coverage   92.37%   92.37%   +<.01%     
==========================================
  Files         166      166              
  Lines       52384    52384              
==========================================
+ Hits        48390    48391       +1     
+ Misses       3994     3993       -1

Flag	Coverage Δ
#multiple	90.8% <ø> (ø)	⬆️
#single	43.02% <ø> (-0.01%)	⬇️

Impacted Files	Coverage Δ
pandas/util/testing.py	88.09% <0%> (+0.09%)	⬆️

---

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[codecov]

Codecov Report

Merging #24650 into master will increase coverage by <.01%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #24650      +/-   ##
==========================================
+ Coverage   92.37%   92.37%   +<.01%     
==========================================
  Files         166      166              
  Lines       52384    52384              
==========================================
+ Hits        48390    48391       +1     
+ Misses       3994     3993       -1

Flag	Coverage Δ
#multiple	90.8% <ø> (ø)	⬆️
#single	43.02% <ø> (-0.01%)	⬇️

Impacted Files	Coverage Δ
pandas/util/testing.py	88.09% <0%> (+0.09%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update dc91f4c...ce0d4e4. Read the comment docs.

[jreback]

thanks @datapythonista

[jorisvandenbossche]

Note for the people doing/reviewing/merging PRs that touch a lot of IPython directive code blocks (eg also the linting clean-up ones, if there will still be coming more), can you please check the travis doc build log ? (there was one failure due to this PR)
It's a bit annoying not to be able to rely on the CI status for that, but that is the reality for now.

[jreback]

w/o automated checks that is not possible to manually do things like this

[jorisvandenbossche]

It is perfectly possible. I do it all the time (when I judge it appropriate to check, like this PR that explicitly tried to fix a lot of ipython directives).

[jreback]

it’s possible but requires more effort which we have traditionally not done
green means it passes

if you don’t agree then we need checks

[jorisvandenbossche]

if you don’t agree then we need checks

And that is what we are working on (see the issue @datapythonista just opened)