Python. How i can iterate over tuples with dict inside : I have some dicts inside tuple

     a = ({'row_n': 1, 'row_section': None, 'nomenclature_platform_id': 'qwe', 'nomenclature_name': 'name', 'TM': ' ', 'no_category': 'orig_num Номер', 'article': 'num артикля', 'size_measures_multi': [('1', 'cm', 'brutto'), ('123', 'm', 'netto_brutto_unknown'), ('1233', 'm', 'netto_brutto_unknown')]}, {'row_n': 2, 'row_section': None, 'nomenclature_platform_id': '34110', 'nomenclature_name': 'Fuel MAX', 'TM': 'Fuel MAX', 'no_category': 'MAGNETICYW', 'article': 'MAGNETICYW', 'size_measures_multi': [('1', 'm', 'netto_brutto_unknown'), ('21', 'm', 'netto_brutto_unknown'), ('28', 'm', 'netto_brutto_unknown')]})

I wont make tuples from key nomenclature_platform_id and every first element from list of tuples, which contain in key 'size_measures_multi', for example

> ('qwe', '1', '123', '1233') 

> ('34110', '1','21','28')

I try make list comprihansion inside tuple

    tuple(a['nomenclature_platform_id'], [item[0] for item in row['size_measures_multi']])


But i have not expected result 

> ('qwe', ['1', '123', '1233'])

> ('34110', ['1','21','28'])


Why my code work wrong and how i can fix it? I will be grateful for the help