user: ### NOW ANSWER:
Question: who are the writer of the series episode number 170?
Columns: ['Season no.', 'Series no.', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. Viewers (millions)']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: [1.0, 156.0, '"Playing Dead"', 'Michael Smith', 'Antoinette Stella', 'April19,2009', 8009.0, '4.57']
SQL:

assistant: SELECT "Written by" FROM "Table" WHERE "Series no." = 170.0;