Computes and optionally renders the Mandelbrot set\index{Mandelbrot set}.
The two positional arguments are optional and allow specification of the
range over which the set is computed (default values: 
[-1.0,2.3] and [-1.3,1.3]).
\gdlkeyworddesc{RESULT}
Allows passing a variable into which the computed data will be sotred.
If set, no rendering is done.
\gdlkeyworddesc{XSIZE}
Allows specification of the width of the domain over which the set is computed.
\gdlkeyworddesc{YSIZE}
Allows specification of the height of the domain over which the set is computed.
\gdlcodeexample{appleman_0}{}{}
