Python - Replace None with Empty Dictionary

# Python3 code to demonstrate working of
# Replace None with Empty Dictionary
# Using recursion + isinstance()

# helper function to perform task


def replace_none(test_dict):

    # checking for dictionary and replacing if None
    if isinstance(test_dict, dict):
      
        for key in test_dict:
            if test_dict[key] is None:
                test_dict[key] = {}
            else:
                replace_none(test_dict[key])

    # checking for list, and testing for each value
    elif isinstance(test_dict, list):
        for val in test_dict:
            replace_none(val)


# initializing dictionary
test_dict = {"Gfg": {1: None, 7: 4}, "is": None,
             "Best": [1, {5: None}, 9, 3]}

# printing original dictionary
print("The original dictionary is : " + str(test_dict))

# calling helper fnc
replace_none(test_dict)

# printing result
print("The converted dictionary : " + str(test_dict))

def replace_none(test_dict):
    # Create a stack with the initial dictionary
    stack = [test_dict]
    
    # While the stack is not empty, process the dictionaries in the stack
    while stack:
        cur_dict = stack.pop()
        # If the current item in the stack is a dictionary, process its key-value pairs
        if isinstance(cur_dict, dict):
            for key, val in cur_dict.items():
                # If the value is None, replace it with an empty dictionary
                if val is None:
                    cur_dict[key] = {}
                # If the value is a dictionary or a list, push it onto the stack
                elif isinstance(val, (dict, list)):
                    stack.append(val)
        # If the current item in the stack is a list, process its elements
        elif isinstance(cur_dict, list):
            for i, val in enumerate(cur_dict):
                # If the value is None, replace it with an empty dictionary
                if val is None:
                    cur_dict[i] = {}
                # If the value is a dictionary or a list, push it onto the stack
                elif isinstance(val, (dict, list)):
                    stack.append(val)

# Example usage
test_dict = {"Gfg": {1: None, 7: 4}, "is": None, "Best": [1, {5: None}, 9, 3]}
replace_none(test_dict)
print(test_dict)