code: function(type, pos, dim, canvas){
        canvas.getCtx()[type + "Rect"](pos.x - dim, pos.y - dim, 2*dim, 2*dim);
      }
docs: /*
  Method: render
  
  Renders a square into the canvas.
  
  Parameters:
  
  type - (string) Possible options are 'fill' or 'stroke'.
  pos - (object) An *x*, *y* object with the position of the center of the square.
  dim - (number) The radius (or half-diameter) of the square.
  canvas - (object) A <Canvas> instance.
  
  Example:
  (start code js)
  NodeHelper.square.render('stroke', { x: 10, y: 30 }, 40, viz.canvas);
  (end code)