Final version of searches as submitted by LLF

Your tests for your traversals are failing here. It looks like you need to revisit the code and see what the function is returning/appending to the eventual list to be returned.

One piece of advice I will offer is that you should never set a default variable to a mutable object. The function definition is in the global namespace, and so the assignment ```path=[]``` is only run the first time you call breadth_first_traversal(), so the next time you try running it, you end up with path still linked to whatever it finished up at last time. The normal way around this is to do something like this:
```
def breadth_first_traversal(self, start, path=None):
    if path is None:
        path = []
```