title: How to find all numbers in a list that are not part of a pair - using python 3
body: <p>I am trying to write a python 3 function that finds all numbers in a list (unspecified length) that are not part of a pair. </p>
  
  <p>For example, given the list <code>[1, 2, 1, 3, 2]</code>, the function will return 3; and given the list <code>[0, 1, 1, 7, 8, 3, 9, 3, 9]</code>, the function will return 0, 7, and 8.</p>
  
  <p>Thanks for your help!</p>