title: Subtract and add two lists without changing their order in Python
body: <p>If I have the list <code>[68,31,93,35,10]</code> (all the numbers will be different) and the list <code>[93,0,22,10,99,33,21,9]</code> (again, all the numbers will be different, but may overlap the other list), I need to be able to get exactly <code>[68,31,93,35,10,0,22,99,33,21,9]</code>, where the second list is appended to the first list without duplicates. I also need to be able to get exactly <code>[68,31,35]</code> where the first list has all duplicates in the second list removed. The output always should be the same order as the input. How do I go about this? (A one liner would be nice if it were simple.)</p>