implement: src/closures -- stat aggregation, higher-order functions

[BryanChasko]

topic: closures

closures in rust capture their environment by value or by reference.
different from python lambdas -- rust closures have explicit capture rules.

concepts to demonstrate

• closure syntax: |args| body
• capturing by reference vs by value (move keyword)
• Fn, FnMut, FnOnce trait bounds
• closures as function arguments (higher-order functions)
• returning closures from functions

patriots theme

aggregate patriots season stats using closures passed to fold and map.
build a stat_filter closure factory for different position groups.

file

src/closures/stat_aggregator.rs

reference

python mirror: libraries_2_statistics_2023_patriots_qb_shuffle.py