character; vector from which to parse options
(default: commandArgs() )
Usage information is generated from opt_get calls made prior to
opt_help. opt_help shused will will not be shown. It is considered best practice to handle all
option parsing in a block at the beginning of the application. opt_help()
would be best placed at the end of that block
Value
logical; returns TRUE if command-line options contain a help flag,
FALSE otherwise. Mainly opt_help is used for side-effects of
printing usage/help information,