+ #
+ # @example
+ #
+ # client = Google::APIClient.new
+ # key = Google::APIClient::PKCS12.load_key('client.p12', 'notasecret')
+ # service_account = Google::APIClient::JWTAsserter(
+ # '123456-abcdef@developer.gserviceaccount.com',
+ # 'https://www.googleapis.com/auth/prediction',
+ # key)
+ # client.authorization = service_account.authorize
+ # client.execute(...)