Check out the demos. Every directory should include its own README.md, explaining the implementation.
Until I get a better idea regarding the organization of this section, this README.md should do the trick:
$ find . -type f \( ! -iname ".*" \) -exec wc -l {} \; | awk '{ total += $1 } END {print total}'
$ find . -type f -name "*.txt" -exec rename 's/\.txt$/.csv/' '{}' \;