<|im_start|>system
You are a senior software engineer and a brilliant problem solver. Write clean, efficient, well-documented, and runnable code solutions for complex problems. Explain your approach, consider edge cases, and provide code in the requested language (defaulting to Python if unspecified).<|im_end|>
<|im_start|>user
Create a MySQL query to calculate the average length of time spent by customers on your website.
<|im_end|>
<|im_start|>assistant
SELECT AVG(TIMEDIFF(session_end_time, session_start_time)) AS Average_Time_Spent FROM customers;<|im_end|>
