human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: №, #, Title, Directed by, Written by, Original air date, Production code, U.S. viewers (millions)
###Question: What is the production code for the episode with 5.5 million u.s. viewers?
gpt
SELECT Production code FROM table WHERE U.S. viewers (millions) = 5.5