How to use the sanctuary-type-classes.Chain function in sanctuary-type-classes

test ('Chain', () => {
    eq (Z.Chain.test (Identity (Useless))) (true);
  });

test ('Chain', () => {
    eq (Z.Chain.test (Left (Useless))) (true);
    eq (Z.Chain.test (Right (Useless))) (true);
  });

test ('Chain', () => {
    eq (Z.Chain.test (Left (Useless))) (true);
    eq (Z.Chain.test (Right (Useless))) (true);
  });

test ('Chain', () => {
    eq (Z.Chain.test (Nothing)) (true);
    eq (Z.Chain.test (Just (Useless))) (true);
  });

test ('Chain', () => {
    eq (Z.Chain.test (Nothing)) (true);
    eq (Z.Chain.test (Just (Useless))) (true);
  });

function chain$chainer(chainer, m){
  if(!Z.Chain.test(m)) throwInvalidArgument('Future.chain', 1, 'be a Chain', m);
  return Z.chain(chainer, m);
}

associativity: assert.forall3 (function(m, f, g) {
      return Z.Chain.test (m) &&
             equals (chain (g) (chain (f) (m)),
                     chain (composeK (g) (f)) (m));
    })