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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 writer(datasets, dataset_names, output_dir):
 """Write the results."""

    for dataset, dataset_name in zip(datasets, dataset_names):
        if dataset:
            filepath = output_dir + '/' + dataset_name + '.txt'
            with open(filepath, 'w+') as out_file:
                joined = '\n'.join(dataset)
                out_file.write(str(joined.encode('utf-8').decode('utf-8')))
                out_file.write('\n')