An argument that takes a true/false value.

The argument should be 0 or 1. The option is output to gnuplot as trueval if the argument is true or falseval if the argument is false. Either one can be None, in which case nothing is output. default should also be 0 or 1.

__call__ ( self,  keyw )

__init__ (
        self,
        argname,
        trueval,
        falseval,
        fixedword=None,
        default=None,
        )