Hi,

Great project! Finally had a chance to check this out with a real use case of my own.

I had an issue getting the instructions to work. Not sure if it was my end or not, but what worked for me was:

decoders = [OpenAPICodec(), JSONCodec()]
client = Client(decoders=decoders)  
schema = client.get('http://petstore.swagger.io/v2/swagger.json', force_codec='openapi')

The error I get using format='openapi' is:

coreapi.exceptions.NoCodecAvailable: Unsupported media in Content-Type header 'application/json'

I noticed that everything seemed to work with the cli client. That's when I noticed that it uses force_codec and not format.

I don't know your code base so I'm not 100% if using force_code is correct in this context, but I thought I should create a ticket in case it hits anyone else.