code: def test_contour(self):
      mpl.rcParams["date.converter"] = "concise"
      range_threshold = 10
      fig, (ax1, ax2, ax3) = plt.subplots(3, 1, layout="constrained")
  
      x_dates = np.array(
          [
              datetime.datetime(2023, 10, delta)
              for delta in range(1, range_threshold)
          ]
      )
      y_dates = np.array(
          [
              datetime.datetime(2023, 10, delta)
              for delta in range(1, range_threshold)
          ]
      )
      x_ranges = np.array(range(1, range_threshold))
      y_ranges = np.array(range(1, range_threshold))
  
      X_dates, Y_dates = np.meshgrid(x_dates, y_dates)
      X_ranges, Y_ranges = np.meshgrid(x_ranges, y_ranges)
  
      Z_ranges = np.cos(X_ranges / 4) + np.sin(Y_ranges / 4)
  
      ax1.contour(X_dates, Y_dates, Z_ranges)
      ax2.contour(X_dates, Y_ranges, Z_ranges)
      ax3.contour(X_ranges, Y_dates, Z_ranges)
  
imports: import datetime
  import numpy
  import pytest
  import matplotlib.pyplot
  import matplotlib
label_desc: Use image node_id 16 for calling the TestDatetimePlotting obj's underlying member method code with example usage: obj.test_contour() without return types