I am trying to install gulp - which seems to require first cask:

    17:14:34/mozaik-demo $brew install gulp
    Error: No available formula for gulp
    Searching formulae...
    Searching taps...
    Caskroom/cask/gulp

Let us install the cask:

    17:14:41/mozaik-demo $brew cask install gulp
    ==> Downloading https://github.com/sindresorhus/gulp-app/releases/download/0.1.0/gulp.app.zip
    ######################################################################## 100.0%
    ==> Symlinking App 'gulp.app' to '/Users/steve/Applications/gulp.app'
    🍺  gulp staged at '/opt/homebrew-cask/Caskroom/gulp/0.1.0' (830 files, 75M)

But then what is the correct next step? Here is my attempt:

    17:15:03/mozaik-demo $brew install gulp
    Error: No available formula for gulp
    Searching formulae...
    Searching taps...
    Caskroom/cask/gulp
    17:15:09/mozaik-demo $which gulp