Sometimes when you are distributing a standalone lib you want to exclude files from the library. Instead you want them to be looked up on the window. That is where browserify-global-lookup comes in handy.
browserify src/index.js \
--standalone Module \
--external backbone \
--external underscore \
| global-lookup-shim.js \
--global-shim underscore:_ \
--global-shim backbone:Backbone \
> dist/build.js