The GetoptLong class allows you to parse command line options similarly to the
GNU getopt_long() C library call. Note, however, that GetoptLong is a pure Ruby
implementation.

GetoptLong allows for POSIX-style options like --file as well as single letter
options like -f

The empty option -- (two minus symbols) is used to end option processing. This
can be particularly important if options have optional arguments.

WWW: https://github.com/ruby/getoptlong