title: Combinations of 2 lists
body: <pre><code>Input: [1, 2, 3] [a, b]
  
  Expected Output: [(1,a),(1,b),(2,a),(2,b),(3,a),(3,b)]
  </code></pre>
  
  <p>This works, but is there a better way without an if statement?</p>
  
  <pre><code>[(x,y) for (x,y) in list(combinations(chain(a,b), 2)) if x in a and y in b]
  </code></pre>