ampl.eval('set A dimen 2;');
A = ampl.getSet('A').get();
A.setValues({ {1, 'a'}, {2, 'b'}});
A
% Alternative way, with tuples
ampl.eval('set B dimen 2;');
B = ampl.getSet('B').get();
t1 = Tuple({1, 'a'});
t2 = Tuple({2, 'b'});
B.setValues({t1, t2});
B