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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _attach_fields(obj):
 """Attach all the marshmallow fields classes to ``obj``, including Flask-Marshmallow's custom fields. """

    for attr in base_fields.__all__:
        if not hasattr(obj, attr):
            setattr(obj, attr, getattr(base_fields, attr))
    for attr in fields.__all__:
        setattr(obj, attr, getattr(fields, attr))