CLI

[rgarcia]

Things like underscore-cli struggle on large files/not streaming their input: https://github.com/ddopson/underscore-cli#efficienct-stream-processing-for-set-oriented-commands-like-map

A use case for us would be streaming in a large json file and extracting a compound key. I've yet to see a command-line json tool that streams its input, so I don't think there's an off-the-shelf solution we could use.