Spreadsheet installation

Prepare

1. Open Client.gs in an editor
2. Change URL in UrlFetchApp.fetch() to point to your python script

Add code

1. Open a Google Spreadsheet
2. Open the Script Editor (Tools > Script editor...)
3. Paste in the contents of Client.gs into Code.gs

Add trigger

The trigger cannot be attached to onEdit() for security reasons, because it calls UrlFetchApp

1. From the Script Editor, open the triggers dialog (Resources > Current project's triggers...)
2. Click the link to "Add a new trigger"
3. Use these settings in the three dropdowns: cacheChanges | From spreadsheet | On change
4. Don't forget to click "Save"