Python transform json keys

transformJson.py

def transformJsonKeys(obj, func=(lambda x: x)):
    if isinstance(obj, list):
        return [transformJsonKeys(element, func) for element in obj]
    elif isinstance(obj, dict):
        return {func(key): transformJsonKeys(value, func) for key, value in obj.items()}
    else:
        return obj


dic = {'k1': 1, 'k2': 2, 'k3': [{'k31': 31, 'k2': 32, 'k33': 33}]}
f = lambda x: "*" + x.capitalize()
print(transformJsonKeys(dic,f))
#{'*K1': 1, '*K2': 2, '*K3': [{'*K31': 31, '*K32': 32, '*K33': 33}]}