Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_21146729_6 ( director VARCHAR, writer_s_ VARCHAR )

### Question ###
Who was the director when the writer(s) was John W. Bloch?

### Accurate SQL ###

SELECT director FROM table_21146729_6 WHERE writer_s_ = "John W. Bloch"