code: def test_plot_pacf_small_sample():
      idx = [
          pd.Timestamp.now() + pd.Timedelta(seconds=i)
          for i in range(10)
      ]
      df = pd.DataFrame(index=idx, columns=["a"], data=list(range(10)))
      plot_pacf(df)
  
imports: from statsmodels.compat.pandas import MONTH_END
  from statsmodels.compat.python import lmap
  import calendar
  from io import BytesIO
  import locale
  import numpy
  from numpy.testing import assert_, assert_equal
  import pandas
  import pytest
  from statsmodels.datasets import elnino, macrodata
  from statsmodels.graphics.tsaplots import month_plot, plot_accf_grid, plot_acf, plot_ccf, plot_pacf, plot_predict, quarter_plot, seasonal_plot
  from statsmodels.tsa import arima_process
  from statsmodels.tsa.ar_model import AutoReg
  from statsmodels.tsa.arima.model import ARIMA
label_desc: Use image node_id 14 for calling a global function with example usage: test_plot_pacf_small_sample() without return types