user: Question: How many directors worked on the episode written by Brent Fletcher & Miranda Kwok?
Columns: ['No.', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code', 'U.S. viewers (million)']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, '" The Red Serpent "', 'Rick Jacobson', 'Steven S. DeKnight', 'January22,2010', 'SPS101', '0.66']
SQL:

assistant: SELECT COUNT("Directed by") FROM "Table" WHERE "Written by" = 'Brent Fletcher & Miranda Kwok';