Database: voter_1
Question: List the area codes in which voters voted both for the contestant 'Tabatha Gehling' and the contestant 'Kelly Clauss'.
SQL: select t3.area_code from contestants as t1 join votes as t2 on t1.contestant_number  =  t2.contestant_number join area_code_state as t3 on t2.state  =  t3.state where t1.contestant_name  =  'tabatha gehling' intersect select t3.area_code from contestants as t1 join votes as t2 on t1.contestant_number  =  t2.contestant_number join area_code_state as t3 on t2.state  =  t3.state where t1.contestant_name  =  'kelly clauss'