# `function` can modify input in-place causing column to be already removed.
                    if column in inputs_to_merge:
                        inputs_to_merge.pop(column)
                    if returned_lazy_dict and column in processed_inputs:
                        processed_inputs.pop(column)
            if check_same_num_examples:
                input_num_examples = len(pa_inputs)
                processed_inputs_num_examples = len(processed_inputs[next(iter(processed_inputs.keys()))])
                if input_num_examples != processed_inputs_num_examples:
                    raise NumExamplesMismatchError()
            if isinstance(inputs, Mapping) and isinstance(processed_inputs, Mapping):
                # The .map() transform *updates* the dataset:
                # the output dictionary contains both the the input data and the output data.
                # The output dictionary may contain Arrow values from `inputs_to_merge` so that we can re-write them efficiently.