user: Question: Who were the guests in the episode with production code 6021? 
Columns: ['Episode #', 'The Wørd', 'Guest', 'Introductory phrase', 'Original airdate', 'Production code']
Types: ['real', 'text', 'text', 'text', 'text', 'real']
Sample row: [669.0, '"Siren Song"', 'Nicole Miller, Jessica Smith, Harold Ford, Jr.', 'None', 'February 1', 6017.0]
SQL:

assistant: SELECT "Guest" FROM "Table" WHERE "Production code" = 6021.0;