text: #!/usr/bin/env python3
  
  import numpy as np
  import pandas as pd
  import string
  
  df = pd.DataFrame(
      {
          "alpha": [c for c in string.ascii_lowercase],
          "c1": range(1 * 26),
          "c2": range(1 * 26, 2 * 26),
          "c3": range(2 * 26, 3 * 26),
          "c4": range(3 * 26, 4 * 26),
      }
  )
  df.set_index("alpha", inplace=True)
  
  print("INDEX: ", df.index.names)
  print(df)
  print()
  
  new_df = df.copy()
  print("INDEX: ", new_df.index.names)
  print(new_df)
  assert new_df.index.names == ["alpha"]
  