Module Getopt::Long implements an extended getopt function called
GetOptions(). This function implements the POSIX standard for command
line options, with GNU extensions, while still capable of handling the
traditional one-letter options.

In general, this means that command line options can have long names
instead of single letters, and are introduced with a double dash `--'.

Optionally, Getopt::Long can support the traditional bundling of
single-letter command line options.