How many people wrote episode 9 in the season that was directed by Ernest Dickerson?
CREATE TABLE table_31007 (
    "No. in series" real,
    "No. in season" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "U.S. viewers (millions)" text
)
SELECT COUNT("Written by") FROM table_31007 WHERE "Directed by" = 'Ernest Dickerson' AND "No. in season" = '9'
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: How many people wrote episode 9 in the season that was directed by Ernest Dickerson? ### Input: CREATE TABLE table_31007 (
    "No. in series" real,
    "No. in season" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "U.S. viewers (millions)" text
) ### Response: SELECT COUNT("Written by") FROM table_31007 WHERE "Directed by" = 'Ernest Dickerson' AND "No. in season" = '9'