https://www.boardmanual.com/2021/summer/data-modeling/2_Database_design_functions/1_Entities/Unbalanced_hierarchies.htm?rhsearch=unbalanced&rhhlterm=unbalanced
https://www.wthr.com/article/news/nation-world/cash-app-duplicate-charges/507-1664eb14-ce74-4abf-9ef5-824d3092ac4a
