class_docstr: Test that wire lines are produced correctly in different situations.
class_docstr_tok: ["Test","that","wire","lines","are","produced","correctly","in","different","situations","."]
docstr: Test wire length when circuit has three layers.
code: def test_three_layers(self):
      """Test wire length when circuit has three layers."""
  
      with qml.queuing.AnnotatedQueue() as q_tape:
          qml.PauliX(0)
          qml.PauliX(0)
          qml.PauliX(0)
  
      tape = QuantumScript.from_queue(q_tape)
      _, ax = tape_mpl(tape)
  
      assert len(ax.lines) == 1
      assert ax.lines[0].get_xdata() == (
          -1,
          3,
      )  # from -1 to number of layers
      assert ax.lines[0].get_ydata() == (0, 0)
  
      plt.close()
  
imports: import pytest
  import pennylane
  from pennylane.drawer import tape_mpl
  from pennylane.tape import QuantumScript
label_desc: Use image node_id 3 for calling the TestWires obj's underlying member method code with example usage: obj.test_three_layers() without return types