user: Question: Who directed all the episodes that were written by Aaron Ehasz & John O'Bryan?
Columns: ['No. in series', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code']
Types: ['real', 'text', 'text', 'text', 'text', 'real']
Sample row: [0.0, '"Unaired Pilot"', 'Dave Filoni', 'Michael Dante DiMartino & Bryan Konietzko', 'Unaired', 100.0]
SQL:

assistant: SELECT "Directed by" FROM "Table" WHERE "Written by" = 'Aaron Ehasz & John O''Bryan';