Wondering about APIViews in Django

Hi I'm working on a Django site and am trying to figure out what the previously implemented code does. I'm new to Django so just figuring this stuff out on the fly. I'm looking at resources.py, and there's a snippet of code that looks like this:

class BaseQueryView(APIView):

def _parse_filter_values(self, data):

   include = []

   exclude = []

   for d in data:

and so on

I guess what I'm wondering is where is the APIView getting the "data" from? How can I find out how "data" is structured?