class_docstr: Tests for the ``Wires`` class.
docstr: Tests the ``index()`` method.
code: def test_index_method(self, iterable):
      """Tests the ``index()`` method."""
  
      wires = Wires(iterable)
      element = iterable[1]
      # check for non-Wires inputs
      assert wires.index(element) == 1
      # check for Wires inputs
      assert wires.index(Wires([element])) == 1
      # check that Wires of length >1 produce an error
      with pytest.raises(WireError, match="Can only retrieve index"):
          wires.index(Wires([1, 2]))
      # check that error raised when wire does not exist
      with pytest.raises(
          WireError, match="Wire with label d not found"
      ):
          wires.index(Wires(["d"]))
  
imports: import pytest
  import numpy
  import pennylane
  from pennylane.wires import Wires, WireError
label_desc: Use image node_id 23 for calling the TestWires obj's underlying member method code with example usage: obj.test_index_method(iterable) without return types