from google.appengine.api import search
search.Document(doc_id='document id', fields=[search.TextField(name=
    'subject', value='going for dinner'), search.HtmlField(name='body',
    value='<html>I found a place.</html>'), search.TextField(name=
    'signature', value='brzydka pogoda', language='pl')], language='en')
Using Search API Python - Google App Engine Big Table