code: def test_fill(self):
      mpl.rcParams["date.converter"] = "concise"
      fig, (ax1, ax2, ax3, ax4) = plt.subplots(
          4, 1, layout="constrained"
      )
  
      np.random.seed(19680801)
  
      x_base_date = datetime.datetime(2023, 1, 1)
      x_dates = [x_base_date]
      for _ in range(1, 5):
          x_base_date += datetime.timedelta(
              days=np.random.randint(1, 5)
          )
          x_dates.append(x_base_date)
  
      y_base_date = datetime.datetime(2023, 1, 1)
      y_dates = [y_base_date]
      for _ in range(1, 5):
          y_base_date += datetime.timedelta(
              days=np.random.randint(1, 5)
          )
          y_dates.append(y_base_date)
  
      x_values = np.random.rand(5) * 5
      y_values = np.random.rand(5) * 5 - 2
  
      ax1.fill(x_dates, y_values)
      ax2.fill(x_values, y_dates)
      ax3.fill(x_values, y_values)
      ax4.fill(x_dates, y_dates)
  
imports: import datetime
  import numpy
  import pytest
  import matplotlib.pyplot
  import matplotlib
label_desc: Use image node_id 20 for calling the TestDatetimePlotting obj's underlying member method code with example usage: obj.test_fill() without return types