code: def test_unfilled(self):
      x, y = [1, 2, 3], [1, 2, 1]
      c = ".5"
      p = Plot(x=x, y=y).add(Area(fill=False, color=c)).plot()
      ax = p._figure.axes[0]
      poly = ax.patches[0]
      assert poly.get_facecolor() == to_rgba(c, 0)
  
file_path: seaborn/tests/_marks/test_area.py
imports: import matplotlib
  from matplotlib.colors import to_rgba, to_rgba_array
  from numpy.testing import assert_array_equal
  from seaborn._core.plot import Plot
  from seaborn._marks.area import Area, Band
label_desc: Use image node_id 4 for calling the TestArea obj's underlying member method code with example usage: obj.test_unfilled() without return types