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 Dogs (age INTEGER, dog_id VARCHAR); CREATE TABLE Treatments (age INTEGER, dog_id VARCHAR)
### Question:
What is the average age of the dogs who have gone through any treatments?
### Answer:
SELECT AVG(age) FROM Dogs WHERE dog_id IN (SELECT dog_id FROM Treatments)