title: Join list2 for every string in list1
body: <p>I have two lists already set up like this</p>
  
  <pre><code>List1 = ["A", "B", "C"]
  List2 = ["1", "2", "3", "4", "5"]
  </code></pre>
  
  <p>I want to join every string of list2 for every string in list1, for example, I would want the final result of the above lists to look like this in a text file:</p>
  
  <pre><code>A:1
  A:2
  A:3
  A:4
  A:5
  B:1
  B:2
  B:3
  B:4
  B:5
  C:1
  C:2
  C:3
  C:4
  C:5
  </code></pre>
  
  <p>Is this achievable? </p>