How can I make this function faster?

[ichabod801]

For one thing, you're testing original within the loop. I would think it would be faster to check original once, and only loop if it's a dict. Also, is it common or rare that it's not a dict? If it's common, and if statement is generally faster; if it's rare, a try/except block is generally faster. And (not familiar with yaml) what is it if it's not a dict? Could testing for that be faster? The same applies for your index error. I would guess not creating a separate variable fro num would be faster, but probably not significantly.