What is the production code of the episode written by Cathryn Humphris?
CREATE TABLE table_27236 (
    "No." real,
    "#" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "Production code" text,
    "U.S. viewers (million)" text
)
SELECT "Production code" FROM table_27236 WHERE "Written by" = 'Cathryn Humphris'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What is the production code of the episode written by Cathryn Humphris? ### Input: CREATE TABLE table_27236 (
    "No." real,
    "#" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "Production code" text,
    "U.S. viewers (million)" text
) ### Response: SELECT "Production code" FROM table_27236 WHERE "Written by" = 'Cathryn Humphris'