code: def test_vlines(self):
      mpl.rcParams["date.converter"] = "concise"
      fig, (ax1, ax2, ax3) = plt.subplots(3, 1, layout="constrained")
      ax1.set_xlim(
          left=datetime.datetime(2023, 1, 1),
          right=datetime.datetime(2023, 6, 30),
      )
      ax1.vlines(
          x=[
              datetime.datetime(2023, 2, 10),
              datetime.datetime(2023, 5, 18),
              datetime.datetime(2023, 6, 6),
          ],
          ymin=[0, 0.25, 0.5],
          ymax=[0.25, 0.5, 0.75],
      )
      ax2.set_xlim(left=0, right=0.5)
      ax2.vlines(
          x=[0.3, 0.35],
          ymin=[
              np.datetime64("2023-03-20"),
              np.datetime64("2023-03-31"),
          ],
          ymax=[
              np.datetime64("2023-05-01"),
              np.datetime64("2023-05-16"),
          ],
      )
      ax3.set_xlim(
          left=datetime.datetime(2023, 7, 1),
          right=datetime.datetime(2023, 12, 31),
      )
      ax3.vlines(
          x=[
              datetime.datetime(2023, 9, 1),
              datetime.datetime(2023, 12, 10),
          ],
          ymin=datetime.datetime(2023, 1, 15),
          ymax=datetime.datetime(2023, 1, 30),
      )
  
imports: import datetime
  import numpy
  import pytest
  import matplotlib.pyplot
  import matplotlib
label_desc: Use image node_id 51 for calling the TestDatetimePlotting obj's underlying member method code with example usage: obj.test_vlines() without return types