user: Question: List all season numbers with production codes of 5M21.
Columns: ['Series #', 'Season #', 'Title', 'Directed by', 'Written by', 'Original air date', 'Production code']
Types: ['real', 'real', 'text', 'text', 'text', 'text', 'text']
Sample row: [91.0, 1.0, '"Friends and Lovers"', "Bill D'Elia", 'David E. Kelley', 'October29,2001', '5M01']
SQL:

assistant: SELECT "Season #" FROM "Table" WHERE "Production code" = '5M21';