Use callback docstring for all solvers and solve the bug with the arrow being printed too far with verbose

[MaxenceGollier]

#231

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.15%. Comparing base (e0f214d) to head (8dae1b7).
⚠️ Report is 165 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #234       +/-   ##
===========================================
+ Coverage   61.53%   86.15%   +24.62%     
===========================================
  Files          11       13        +2     
  Lines        1292     1575      +283     
===========================================
+ Hits          795     1357      +562     
+ Misses        497      218      -279     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.