code: def backColor(self, bc=None):
          
          backProp = self.GetBackfaceProperty()
  
          if bc is None:
              if backProp:
                  return backProp.GetDiffuseColor()
              return None
  
          if self.GetProperty().GetOpacity() < 1:
              colors.printc("~noentry backColor(): only active for alpha=1", c="y")
              return self
  
          if not backProp:
              backProp = vtk.vtkProperty()
  
          backProp.SetDiffuseColor(colors.getColor(bc))
          backProp.SetOpacity(self.GetProperty().GetOpacity())
          self.SetBackfaceProperty(backProp)
          self.GetMapper().ScalarVisibilityOff()
          return self
docs: Set/get actor's backface color.