user: Question: Which class has a city of Richmond, Virginia?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['W284BC', 104.7, 'Waldorf, Maryland', 10.0, 'D', 'FCC']
SQL:

assistant: SELECT "Class" FROM "Table" WHERE "City of license" = 'Richmond, Virginia';