Pro-tip: you can use "brew info [package-name]" to lookup the post-install info that flashes up after a homebrew install.

    $ brew info cassandra

    cassandra: stable 2.1.2
    http://cassandra.apache.org
    Not installed
    From: https://github.com/Homebrew/homebrew/blob/master/Library/Formula/cassandra.rb
    ==> Caveats
    If you plan to use the CQL shell (cqlsh), you will need the Python CQL library
    installed. Since Homebrew prefers using pip for Python packages, you can
    install that using:

      pip install cql

    To have launchd start cassandra at login:
        ln -sfv /usr/local/opt/cassandra/*.plist ~/Library/LaunchAgents
    Then to load cassandra now:
        launchctl load ~/Library/LaunchAgents/homebrew.mxcl.cassandra.plist