user: Question: What is the call sign of the translator in Spring Valley, Nevada?
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 "Call sign" FROM "Table" WHERE "City of license" = 'Spring Valley, Nevada';