Empty Response but Status Code is 200

[taylorjdawson]

I was testing out the get_token_balance.py example. I found that there is a case where the response is empty but the status code is 200; An exception is thrown:
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)
The issue is in client.py:

        if req.status_code == 200:
            return json.loads(req.text)

In this case req.text is empty so executing json.loads() on an empty string throws the aforementioned exception.
There should be a check for an empty response. I have implemented a fix but I wanted to check with you before initiating a pull request.

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P.S. This is a fantastic project that I would love contributing to!

[corpetty]

pull away. Thanks for pointing that out.