Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_60 (laps INTEGER, time_retired VARCHAR, driver VARCHAR)
### Question:
What is the mean number of laps when time/retired was spun off and the driver was Nick Heidfeld?
### Answer:
SELECT AVG(laps) FROM table_name_60 WHERE time_retired = "spun off" AND driver = "nick heidfeld"