Marshmallow - это не инструмент для анализа файлов json.marshmallow is an ORM/ODM/framework-agnostic library for converting complex datatypes, such as objects, to and from native Python datatypes.
source: marshmallow.readthedocs.io/en/3.0
Использование json
модуля python для загрузки JSON.
Вот пример, демонстрирующий, как создавать и загружать строки JSON вPython:
import json
# this is how you create a dict object in python
pythonDictExample = {"A":"33","$C":"12"}
# this is how to create a json string from python dict
jsonExample = json.dumps(pythonDictExample)
print("Printing json string")
print(jsonExample)
# this is how you load a json string into a python dict
loadedPythonDict = json.loads(jsonExample)
print("Printing dict (loaded json string)")
print(loadedPythonDict)