The index of the occurrence of the option name, or of the first option parameter. It will be NaN if the sequence comes from an environment variable.
The option name as specified on the command-line, or the environment variable name. It will be the option's preferred name if the sequence comes from positional arguments.
The option parameter(s), or the parameters preceding the word being completed, if any.
The previously parsed values.
It is an opaque type that should be cast to OptionValues<typeof your_options>
.
Information about the current argument sequence in the parsing loop.