user: Question: Name the city of license for call sign of K215ES
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'text', 'text', 'text']
Sample row: ['K257CH', 99.3, 'Estherville, Iowa', '80(@ 53 meters)', 'D', 'FCC']
SQL:

assistant: SELECT "City of license" FROM "Table" WHERE "Call sign" = 'K215ES';