GOOGLE CHART TOOLS FOR DEVELOPERS
Many Google Codes can be found at the 'Code Playground'.
The Google Playground can be found at http://code.google.com/apis/ajax/playground/?type=visualization
For example, pie charts can be found at the playground.
To get a desired chart at the 'Google Playground',
1) Select an option under 'Pick Api'.
2) Select 'View Docs'.
Google Pie Charts
If you want to add a Google pie chart to your website, you can find them at https://developers.google.com/chart/interactive/docs/quick_start or https://developers.google.com/chart/interactive/docs/gallery/piechart