title: Pythonic way to "merge" two lists to a list of tuples
body: <p>Suppose I have two lists</p>
  
  <p><code>L1 = [1,2,3]</code></p>
  
  <p>and </p>
  
  <p><code>L2 = [a,b,c]</code></p>
  
  <p>Whats the fastest way to convert this to the list <code>M = [(1,a),(2,b),(3,c)]</code>?</p>
  
  <p>I tried <code>M = [(x,y) for x in L1 for y in L2]</code> but this gives me all possible combination of elements. Sure I can write a loop to do it, but is there a more pythonic way to do this?</p>