In Python, you can merge two nested dicts or apply functions over them even if them nested, yes!

why_people_letting_python_be_a_major_languıage_questionmark.py

def apply_with(d, fn=lambda x: x):
    res = d.copy() # "= dict(d1)" for lists of tuples
    for key, val in res.items():
        if type(res[key]) is dict:
            res[key] = apply_with(res[key], fn)
        else:
            res[key] = fn(res[key])
    return res

def merge_with(d1, d2, fn=lambda x, y: x + y):
    # print("---------merging---------")
    # print('d1: {}, d2: {}'.format(d1, d2))
    res = d1.copy() # "= dict(d1)" for lists of tuples
    for key, val in d2.items(): # ".. in d2" for lists of tuples
        try:
            if type(res[key]) is dict:
                #print('dict')
                #print(key)
                #print(res[key])
                res[key] = merge_with(res[key], val, fn)
            else:
                #print('scaler')
                #print(key)
                res[key] = fn(res[key], val)
                #print(res[key])
        except: #KeyError:res[key] = val
            pass
    #print("res: {}".format(res))
    #print("--------------------")
    return res