Help is given as structure listing command and their parameters in a
short/compressed form.

help        = dict (name -> command)
name        = string
command     = dict ('desc'      -> description
		    'options'   -> options
		    'arguments' -> arguments)
description = string
options     = list (option...)
option      = dict (name -> description)
arguments   = list (argument...)
argument    = dict (name -> argdesc)
argdesc     = dict ('code' -> code
		    'desc' -> description)
code in {
     +		<=> required
     ?		<=> optional
     +*		<=> required splat
     ?* 	<=> optional splat
}

The conversion of this form into a help text, or other structure is
outside of the scope of xo/cmdr