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 teaches (id VARCHAR, semester VARCHAR, YEAR VARCHAR)
### Question:
Find the id of instructors who taught a class in Fall 2009 but not in Spring 2010.
### Answer:
SELECT id FROM teaches WHERE semester = 'Fall' AND YEAR = 2009 EXCEPT SELECT id FROM teaches WHERE semester = 'Spring' AND YEAR = 2010