PostgreSql - Função para validar estado (UF) brasileiro

CREATE OR REPLACE FUNCTION public.is_valid_uf(p_uf varchar) RETURNS boolean AS
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BEGIN
RETURN upper(p_uf) = ANY (string_to_array('AC,AL,AM,AP,BA,CE,DF,ES,GO,MA,MG,MS,MT,PA,PB,PE,PI,PR,RJ,RN,RO,RR,RS,SC,SE,SP,TO', ','));
END;
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LANGUAGE 'plpgsql';