code: def test_single_paired_var(self, var):
      other_var = {"x": "y", "y": "x"}[var]
      pairings = ["x", "y", "z"]
      pair_spec = {
          "variables": {f"{var}{i}": v for i, v in enumerate(pairings)},
          "structure": {
              var: [f"{var}{i}" for i, _ in enumerate(pairings)]
          },
      }
  
      s = Subplots({}, {}, pair_spec)
      s.init_figure(pair_spec)
  
      assert len(s) == len(pair_spec["structure"][var])
  
      for i, e in enumerate(s):
          assert e[var] == f"{var}{i}"
          assert e[other_var] == other_var
          assert e["col"] is e["row"] is None
  
      tests = i == 0, True, True, i == len(s) - 1
      sides = {
          "x": ["left", "right", "top", "bottom"],
          "y": ["top", "bottom", "left", "right"],
      }
  
      for side, expected in zip(sides[var], tests):
          assert e[side] == expected
  
imports: import itertools
  import numpy
  import pytest
  from seaborn._core.subplots import Subplots
label_desc: Use image node_id 5 for calling the TestSubplotElements obj's underlying member method code with example usage: obj.test_single_paired_var(var) without return types