user: Question: What call sign has a frequency of 91.3 MHz?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['K217EZ', 91.3, 'Coachella, California', 10.0, 'D', 'FCC']
SQL:

assistant: SELECT "Call sign" FROM "Table" WHERE "Frequency MHz" = 91.3;