text: import unittest
  import pandas as pd
  import numpy as np
  
  import main
  
  
  class MyTestCase(unittest.TestCase):
      def test_something(self):
          df = pd.DataFrame(np.random.randint(0, 100, size=(100, 4)), columns=list('ABCD'))
  
          first, last = main.split_last(df, 30)
  
          self.assertEqual(len(df), len(first) + len(last))
  
  
  
  if __name__ == '__main__':
      unittest.main()
  