[MAINT] extract dataset ids and file lists

[Remi-Gau]

• Closes extract dataset IDs in separate functions #3704

[codecov]

Codecov Report

Merging #3890 (3ca8fdb) into main (c9b8c7f) will increase coverage by 0.00%.
The diff coverage is 91.30%.

@@           Coverage Diff           @@
##             main    #3890   +/-   ##
=======================================
  Coverage   91.61%   91.61%           
=======================================
  Files         134      134           
  Lines       15723    15730    +7     
  Branches     3274     3274           
=======================================
+ Hits        14404    14411    +7     
  Misses        770      770           
  Partials      549      549           

Flag	Coverage Δ
macos-latest_3.10	91.53% <91.30%> (+<0.01%)	⬆️
macos-latest_3.11	91.53% <91.30%> (+<0.01%)	⬆️
macos-latest_3.8	91.50% <91.30%> (+<0.01%)	⬆️
macos-latest_3.9	91.50% <91.30%> (+<0.01%)	⬆️
ubuntu-latest_3.10	91.53% <91.30%> (+<0.01%)	⬆️
ubuntu-latest_3.11	91.53% <91.30%> (+<0.01%)	⬆️
ubuntu-latest_3.8	91.50% <91.30%> (+<0.01%)	⬆️
ubuntu-latest_3.9	91.50% <91.30%> (+<0.01%)	⬆️
windows-latest_3.10	?
windows-latest_3.11	?
windows-latest_3.8	91.44% <91.30%> (+<0.01%)	⬆️
windows-latest_3.9	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
nilearn/datasets/func.py	78.66% <90.00%> (+0.14%)	⬆️
nilearn/datasets/struct.py	90.85% <100.00%> (+0.10%)	⬆️

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[github-actions]

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[ymzayek]

LGTM thx!