Test for solution of first task of https://github.com/ton-blockchain/func-contest2

test.fc

int __test_t30_12() {
  int a = 30;
  int b = 12;
  tuple stack = unsafe_tuple([a, b]);
  cell data = begin_cell().end_cell();
  var (int gas_used, ret_stack) = invoke_method(gcd, stack);
  int result = first(ret_stack);
  throw_if(101, result != 6);
  return gas_used;
}