anychart.onDocumentReady(function () {
var chart = anychart.pie([
{x: 'Cycling', value: 12},
{x: 'Swimming', value: 14},
{x: 'Hiking', value: 12},
{x: 'Alpinism', value: 20}
chart.stroke(function () {
return anychart.color.setThickness(anychart.color.darken(this.sourceColor), 3);
chart.title('Set chart stroke parameters as a function');
chart.container('container');