These functions list the options in their group. The optional argument
arg is a symbol which modifies the form in which the options are
presented.
With no arguments, <group>-options returns the values of the
options in that particular group. If arg is 'help, a
description of each option is given. If arg is 'full,
programmers' options are also shown.
arg can also be a list representing the state of all options. In
this case, the list contains single symbols (for enabled boolean
options) and symbols followed by values.
