user: Question: What is the class of the translator with 10 ERP W and a call sign of W273BL?
Columns: ['Call sign', 'Frequency MHz', 'City of license', 'ERP W', 'Class', 'FCC info']
Types: ['text', 'real', 'text', 'real', 'text', 'text']
Sample row: ['K220IV', 91.9, 'North Pole, Alaska', 62.0, 'D', 'FCC']
SQL:

assistant: SELECT "Class" FROM "Table" WHERE "ERP W" = 10.0 AND "Call sign" = 'W273BL';