user: Question: When there are  12.70 million u.s. viewers who is the director?
Columns: ['Series #', 'Title', 'Directed by', 'Written by', 'U.S. viewers (million)', 'Original airdate', 'Production Code']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'real']
Sample row: [1.0, '" Premiere "', 'Doug Liman', 'Josh Schwartz', '7.5', 'August5,2003', 475197.0]
SQL:

assistant: SELECT "Directed by" FROM "Table" WHERE "U.S. viewers (million)" = '12.70';