These types represent options. Option names cannot have a dash as their first or second character, and long option names cannot have an equals sign anywhere in the name.
Short options. Options that are preceded with a single dash on the command line and consist of a single letter. That single letter cannot be a dash. Any other Unicode character is good (including pathological ones like newlines).
Creates a short option. Returns Nothing if the character is not valid for a short option.
Long options. Options that are preceded with two dashes on the
command line and typically consist of an entire mnemonic word, such
lines. However, anything that is at least one letter long is
fine for a long option name. The name must not have a dash as
either the first or second character and it must be at least one
character long. It cannot have an equal sign anywhere in its
name. Otherwise any Unicode character is good (including
pathological ones like newlines).