def METHOD_NAME(fileName, coordString):
    coordDict = json.loads(coordString)
    jsonFileName = fileName.split("/")[-1]  # grab just the filename
    jsonFileName = jsonFileName.replace(".root", "__1_harvest_list.json")
    data = json.load(open(jsonFileName))
    for i, hypo_test in enumerate(data):  # an entry is one hypo test result
        for key in coordDict:  # each item of the result
            # parse input arguments, thanks to Larry for regex suggestions
            total = eval(re.sub(r"\b([a-zA-Z]+[0-9]*)\b", r'hypo_test["\g<1>"]', key))
            # assign new key to value
            hypo_test[coordDict[key]] = total
    with open(jsonFileName, "w") as f:
        f.write(json.dumps(data))