Use x.data instead of x.begin when doing pointer arithmetic

[LegalizeAdulthood]

Fixes #93

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.40%. Comparing base (91a4a91) to head (4641463).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop      #94      +/-   ##
===========================================
- Coverage    99.43%   99.40%   -0.03%     
===========================================
  Files          168      168              
  Lines         7556     7556              
===========================================
- Hits          7513     7511       -2     
- Misses          43       45       +2     

see 1 file with indirect coverage changes

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[LegalizeAdulthood]

the authorship on the commits is wrong, so I'm closing this and will open a new PR with the correct information