This isn't run/tested but a general refactor. What = \ ?

gistfile1.txt

from kivy.adapters.dictadapter import DictAdapter
from kivy.uix.gridlayout import GridLayout
from kivy.uix.listview import ListItemButton
from kivy.uix.listview import ListView

from fixtures import fruit_categories
from fixtures import fruit_data

from fruit_detail_view import FruitDetailView as DetailView


Fixtures = namedtuple('Fixtures', 'categories data')
DATA = Fixtures(fruit_categories, fruit_data)


# A custom adapter is needed here, because we must transform the selected
# fruit category into the list of fruit keys for that category.
class FruitDictAdapter(DictAdapter):

    def on_change(self, adapter, *args):
        if len(adapter.selection) == 0:
            self.data = {}
            return
        category = DATA.categories[adapter.selection[0].text]
        self.sorted_keys = category['fruits']


def args_converter(row_index, rec):
    return {
        'text': rec['name'],
        'size_hint_y': None,
        'height': 25
    }


class CascadingView(GridLayout):
    """Implementation of a cascading style display

    Provides a scrollable list of fruit categories on the left, a list of
    fruits for the selected category in the middle, and a fruit detail view on
    the right.

    This examples uses :class:`DictAdapter`. See an equivalent treatment done
    with :class:`ListAdapter` in list_cascade.py.

    See list_cascade_images.py for the same example, also using
    :class:`DictAdapter`, and with images of fruit in fruit list items and in
    the detail view.

    """

    def __init__(self, **kwargs):
        kwargs['cols'] = 3
        super(CascadingView, self).__init__(**kwargs)

        # Fruit categories list on the left:
        #
        categories = sorted(fruit_categories.keys())
        categories_dict_adapter = DictAdapter(sorted_keys=categories,
                                              data=fruit_categories,
                                              args_converter=args_converter,
                                              selection_mode='single',
                                              allow_empty_selection=False,
                                              cls=ListItemButton)

        categories_list_view = ListView(adapter=dict_adapter,
                                        size_hint=(.2, 1.0))

        self.add_widget(list_view)

        fruits_dict_adapter = FruitsDictAdapter(
            sorted_keys=DATA.categories[categories[0]]['fruits'],
            data=DATA.data,
            args_converter=args_converter,
            selection_mode='single',
            allow_empty_selection=False,
            cls=ListItemButton)

        dict_adapter.bind(on_selection_change=fruits_dict_adapert.on_change)

        fruit_list_view = ListView(adapter=fruits_dict_adapter,
                                   size_hint=(.2, 1.0))

        self.add_widget(fruits_list_view)

        # Detail view, for a given fruit, on the right:
        #
        detail_view = FruitDetailView(
           fruit_name=fruits_dict_adapter.selection[0].text,
           size_hint=(.6, 1.0))

        fruits_dict_adapter.bind(on_selection_change=detail_view.on_change)
        self.add_widget(detail_view)


if __name__ == '__main__':

    from kivy.base import runTouchApp

    runTouchApp(CascadingView(width=800))

I can't say if it reads the same (not knowing exactly what the other code did), but it looks much better without the "= ".