[future]not specification requires target

[vaaaaanquish]

class foo(gokart.TaskOnKart):
    target = gokart.TaskInstancePrameter()

    def run(self):
        self.load_data_frame(required_columns={'foo'})    # AttributeError: 'dict' object has no attribute 'empty'

When the length of the dict is 1, what to load of require task.

[Hi-king]

I think dict output cannot be used with load_data_frame. With load_data_frame keys of dict will be lost.

[Hi-king]

OK, I've realized point is that you need shorthand of self.load_data_frame("target") with self.load_data_frame()

[vaaaaanquish]

merged #180