Plotly updating trace with marker symbol resets marker size

I am using plotly.js .

When i try to update marker.symbol , it resets marker.size

JSFIDDLE: https://jsfiddle.net/bababalcksheep/sa0rbfg8/6/

Code:

var trace1 = {
   x: [1, 2, 3, 4],
   y: [10, 11, 12, 13],
   mode: 'markers',
   marker: {
     size: [40, 60, 80, 100]
   }
 };
 var data = [trace1];
 var layout = {
   title: 'Marker Size',
   showlegend: false,
   height: 400,
   width: 480
 };

 Plotly.newPlot('myDiv', data, layout);
 $('#changes').click(function() {
   var data_update = {
     'marker': {
       symbol: 'square'
     }
   };
   Plotly.restyle('myDiv', data_update, [0]);
 });

Try

Plotly.restyle('myDiv', 'marker.symbol', 'square', [0]);

instead.

thankx it works. documentation should say so as well