new_contents: import unittest
  from aiopg.sa.connection import _distill_params
  
  class _DistillArgsTest(unittest.TestCase):
      def test_distill_none(self):
          self.assertEqual(
              _distill_params(None, None),
              []
          )
  
      def test_distill_no_multi_no_param(self):
          self.assertEqual(
              _distill_params((), {}),
              []
          )
  
      def test_distill_dict_multi_none_param(self):
          self.assertEqual(
              _distill_params(None, {"foo": "bar"}),
              [{"foo": "bar"}]
          )
  
      def test_distill_dict_multi_empty_param(self):
          self.assertEqual(
              _distill_params((), {"foo": "bar"}),
              [{"foo": "bar"}]
          )
  
      def test_distill_single_dict(self):
          self.assertEqual(
              _distill_params(({"foo": "bar"},), {}),
              [{"foo": "bar"}]
          )
  
      def test_distill_single_list_strings(self):
          self.assertEqual(
              _distill_params((["foo", "bar"],), {}),
              [["foo", "bar"]]
          )
  
      def test_distill_single_list_tuples(self):
          self.assertEqual(
              _distill_params(([("foo", "bar"), ("bat", "hoho")],), {}),
              [('foo', 'bar'), ('bat', 'hoho')]
          )
  
      def test_distill_single_list_tuple(self):
          self.assertEqual(
              _distill_params(([("foo", "bar")],), {}),
              [('foo', 'bar')]
          )
  
      def test_distill_multi_list_tuple(self):
          self.assertEqual(
              _distill_params(
                  ([("foo", "bar")], [("bar", "bat")]),
                  {}
              ),
              ([('foo', 'bar')], [('bar', 'bat')])
          )
  
      def test_distill_multi_strings(self):
          self.assertEqual(
              _distill_params(("foo", "bar"), {}),
              [('foo', 'bar')]
          )
  
      def test_distill_single_list_dicts(self):
          self.assertEqual(
              _distill_params(([{"foo": "bar"}, {"foo": "hoho"}],), {}),
              [{'foo': 'bar'}, {'foo': 'hoho'}]
          )
  
      def test_distill_single_string(self):
          self.assertEqual(
              _distill_params(("arg",), {}),
              [["arg"]]
          )
  
      def test_distill_multi_string_tuple(self):
          self.assertEqual(
              _distill_params((("arg", "arg"),), {}),
              [("arg", "arg")]
          )
  
subject: Add tests for _distil_params