text: import numpy as np
  import pandas as pd
  import pytest
  
  
  @pytest.fixture
  def dta():
      return pd.DataFrame.from_dict(
          {
              'A': np.arange(1, 16),
              'B': pd.date_range('2020-01-01', periods=15),
              'C': ['A', 'B', 'C'] * 5,
              'D': pd.Categorical(['A', 'B', 'C'] * 5),
          }
      )
  