Give the alphanumeric ID of the Catholic legislators in Nebraska.
alphanumeric ID refers to bioguide; Catholic legislators refers to religion_bio = 'Catholic'; Nebraska refers to state = 'NE';
SELECT T1.bioguide FROM `current-terms` AS T1 INNER JOIN current AS T2 ON T2.bioguide_id = T1.bioguide WHERE T2.religion_bio = 'Catholic' AND T1.state = 'NE'