@iamed2 pointed this out in #59, here. We do not have consistency between the pop! function for LittleDict and OrderedDict.

LittleDict

Will return nothing if the key is not found.

OrderedDict

Will throw a KeyError if the key is not found.

I propose that we make the following changes:

1. Have LittleDict throw a KeyError when the key is not found.
2. Introduce a new function which provides a default value to return if key DNE (LittleDict pop! default #59)