code: function(node,x,y,size,color,context) {
      context.fillStyle = 'yellow';
      context.beginPath();
      context.arc(x,y,size,1.25*Math.PI,0,false);
      context.arc(x,y,size,0,0.75*Math.PI,false);
      context.lineTo(x,y);
      context.closePath();
      context.fill();
  
      context.fillStyle = 'white';
      context.strokeStyle = 'black';
      context.beginPath();
      context.arc(x+size/3,y-size/3,size/4,0,2*Math.PI,false);
      context.closePath();
      context.fill();
      context.stroke();
  
      context.fillStyle = 'black';
      context.beginPath();
      context.arc(x+4*size/9,y-size/3,size/8,0,2*Math.PI,false);
      context.closePath();
      context.fill();
    }
docs: An example of a non standard shape (pacman). Here we WILL NOT use the
  genericDraw functions, but rather register a full custom node renderer for
  fill, and skip the border renderer which is irrelevant for this shape
  ----------