The Lark application is a command line app for interacting with USB hardware wallets in Bitcoin related functions. It uses the Lark Java library at https://github.com/sparrowwallet/lark, which in turn is a port of the Python library HWI. The Lark command line application is designed to be a drop-in replacement for HWI, with a subset of commands implemented. Documentation on the commands is available by running it with --help.