Installing SASS on OS X El Capitan

Normally, we'd install using the following command:

sudo gem install sass

This returns the following error in OS X El Capitan:

Fetching: sass-3.4.22.gem (100%)
ERROR:  While executing gem ... (Errno::EPERM)
    Operation not permitted - /usr/bin/sass

Instead, use the following as suggested by @endplasmic on Github:

sudo gem install -n /usr/local/bin sass