old_contents: import io
  import json
  import os
  import unittest
  import zipfile
  
  import pandas
  import requests
  
  from estimator import Estimator
  
  
  class TestEstimator(unittest.TestCase):
      def test_movie_lens_1m(self):
          with open(os.path.join(os.path.dirname(__file__), 'movie_lens_1m.json')) as config_file:
              config = json.load(config_file)
          zip_file = zipfile.ZipFile(io.BytesIO(requests.get(config['url']).content))
          data_set = pandas.read_csv(io.StringIO(zip_file.open(config['file']).read().decode('UTF-8')),
                                     sep=config['separator'], header=None, names=config['attributes'], engine='python')
          estimator = Estimator(config, data_set)
          estimator.estimate()
  
new_contents: import io
  import json
  import os
  import unittest
  import zipfile
  
  import pandas
  import requests
  
  import estimator
  
  
  class TestEstimator(unittest.TestCase):
      def test_movie_lens_1m(self):
          with open(os.path.join(os.path.dirname(__file__), 'movie_lens_1m.json')) as config_file:
              config = json.load(config_file)
          zip_file = zipfile.ZipFile(io.BytesIO(requests.get(config['url']).content))
          data_set = pandas.read_csv(io.StringIO(zip_file.open(config['file']).read().decode('UTF-8')),
                                     sep=config['separator'], header=None, names=config['attributes'], engine='python')
          movie_estimator = estimator.Estimator(config, data_set)
          movie_estimator.estimate()
  
subject: refactor import statements