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_name_18 ( production_number INTEGER, title VARCHAR, director VARCHAR, series VARCHAR )

### Question ###
What is the production number directed by Robert McKimson in series mm titled People Are Bunny?

### Accurate SQL ###

SELECT SUM(production_number) FROM table_name_18 WHERE director = "robert mckimson" AND series = "mm" AND title = "people are bunny"