hscale=auto;
a, b, c;
parallel a->b;
parallel symbol shape at b++ 
     [shape=def.trapezoid, xsize=20, 
      fill.color=olive, fill.gradient=up];
symbol ... at a-b [fill.color=black];
a<-b;
symbol arc at a 
     [xsize=10, ysize=10, fill.color=blue, 
      compress=yes];
symbol cross at c [line.color=red];
hide c; 
