Loads the JSON in a ${barcode}_stats.json file in the DNAnexus project (usually in the qc
        folder).

def get_barcode_stats(self, barcode):
        """
        Loads the JSON in a ${barcode}_stats.json file in the DNAnexus project (usually in the qc
        folder). 
        """
        filename = barcode + "_stats.json"
        # In the call to dxpy.find_one_data_object() below, I'd normally set the 
        # more_ok parameter to False, but this blows-up in Python 3.7 - giving me a RuntimeError. 
        # So, I just won't set it for now. I think dxpy is still mainly a Python 2.7 library and
        # can break in later version of Python3. 
        file_id = dxpy.find_one_data_object(
            zero_ok=False,
            project=self.dx_project_id,
            name=filename)["id"]
        json_data = json.loads(dxpy.open_dxfile(file_id).read())
        return json_data