C# Equivalent of Python's itertools.chain
<p>What (if any) is the C# equivalent of Python's itertools.chain method?</p>

<p>Python Example:</p>

<pre><code>l1 = [1, 2]
l2 = [3, 4]
for v in itertools.chain(l1, l2):
    print(v)
</code></pre>

<p>Results:<br>
1<br>
2<br>
3<br>
4  </p>

<p>Note that I'm not interested in making a new list that combines my first two and then processing that.  I want the memory/time savings that itertools.chain provides by not instantiating this combined list.</p>
