public void Keys_1Dimension(JaggedDictionary<int, string> sut, JaggedIndex1<int>[] keys, string value)
        {
            foreach (var key in keys) sut[key] = value;

            var list = sut.Keys.ToList();
            Assert.Equal(keys.Length, list.Count);
            foreach (var item in list)
            {
                Assert.True(keys.Cast<IJaggedIndex<int>>().Contains(item));
            }
        }
        public void Enumerate_1Dimension(JaggedDictionary<int, string> sut, JaggedIndex1<int>[] keys, string value)
        {
            foreach (var key in keys) sut[key] = value;

            var keyValuePairs = sut.ToList();
            Assert.Equal(keys.Length, keyValuePairs.Count);
            foreach (var kvp in keyValuePairs)
            {
                Assert.True(keys.Cast<IJaggedIndex<int>>().Contains(kvp.Key));
                Assert.Equal(value, kvp.Value);
            }
        }