Python get dictionary all nested keys

get_keys.py

def get_keys(dl, key_list):
    if isinstance(dl, dict):
        for k, v in dl.items():
            key_list.append(k)
            if isinstance(v, list) or isinstance(v, dict):
                get_keys(v, key_list)
    if isinstance(dl, list):
        for i in dl:
            if isinstance(i, list) or isinstance(i, dict):
                get_keys(i, key_list)


dic = {'k1': 1, 'k2': 2, 'k3': [{'k31': 31, 'k2': 32, 'k33': 33}]}
keys_list = []
get_keys(dic, keys_list)
print(keys_list)

#[k1,k2,k3,k31,k32,k33]