Itertools Chain on Nested List
<p>I have two lists combined sequentially to create a nested list with python's map and zip funcionality; however, I wish to recreate this with itertools. </p>

<p>Furthermore, I am trying to understand why itertools.chain is returning a flattened list when I insert two lists, but when I add a nested list it simply returns the nested list. </p>

<p>Any help on these two issues would be greatly appreciated. </p>

<pre><code>from itertools import chain

a = [0,1,2,3]
b = [4,5,6,7]

#how can I produce this with itertools?
c = list(map(list, zip(a,b)))
print(c) #[[0, 4], [1, 5], [2, 6], [3, 7]]

d = list(chain(c))
print(d) #[[0, 4], [1, 5], [2, 6], [3, 7]]

d = list(chain(a,b))
print(d) #[0, 1, 2, 3, 4, 5, 6, 7]
</code></pre>