Converion of dictionary to list of tuples (Stackoverflow problem), Python 3

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import json

def get_filtered_data(data_list, parent):
    # print(data_list, parent)
    if not data_list:
        return []

l = []

for d in data_list:
        parents = []
        texts = []

if not parent:
            parents.append(None) # Python has None for Null values , JavaScript has null, C/C++ have NULL
        else:
            parents.append(parent)

texts.append(d['text'])
        # print(zip(parents, texts))
        l = l + list(zip(parents, texts)) + get_filtered_data(d['children'], parent + 1)

return l

# Starting point
if __name__ == "__main__":
    parent = 0

# Input Data
    data = [
        {
        'text':'first_layer 1',
        'children':[
                     {
                       'text':'second_layer 11',
                       'children':[
                                    {
                                      'text':'third_layer 111',
                                      'children': [],
                                    }
                                  ],
                     },
                     {
                       'text':'second_layer 12',
                       'children':[]
                     }
                  ],
        }
    ]
    
    output_list = get_filtered_data(data, parent)
    print(output_list, '\n') # In each tuple, 1st item is parent id, 2nd one is text of current child element
    # [(None, 'first_layer 1'), (1, 'second_layer 11'), (2, 'third_layer 111'), (1, 'second_layer 12')]

# Sorting based on parent id
    output_list2 = sorted(output_list, key=lambda tup: 0 if tup[0] is None else tup[0])
    print(output_list2, '\n')
    # [(None, 'first_layer 1'), (1, 'second_layer 11'), (1, 'second_layer 12'), (2, 'third_layer 111')]

output_list3 = [(index + 1,) + tup for index, tup in enumerate(output_list2)]
    print(output_list3, '\n')
    # [(1, None, 'first_layer 1'), (2, 1, 'second_layer 11'), (3, 2, 'third_layer 111'), (4, 1, 'second_layer 12')]

pretty_output = json.dumps(output_list3, indent=4)  
    print(pretty_output)
    """
    [
        [
            1,
            null,
            "first_layer 1"
        ],
        [
            2,
            1,
            "second_layer 11"
        ],
        [
            3,
            1,
            "second_layer 12"
        ],
        [
            4,
            2,
            "third_layer 111"
        ]
    ]
    """

[ + ] Show input
Absolute running time: 0.13 sec, cpu time: 0.1 sec, memory peak: 7 Mb, absolute service time: 0,14 sec