code: def swapLayerNames(self, layerName, otherLayerName):
          
          layerOrder = self.layerOrder
          layerName = normalizers.normalizeLayerName(layerName)
          if layerName not in layerOrder:
              raise ValueError("No layer with the name '%s' exists." % layerName)
          otherLayerName = normalizers.normalizeLayerName(otherLayerName)
          if otherLayerName not in layerOrder:
              raise ValueError("No layer with the name '%s' exists." % otherLayerName)
          self._swapLayers(layerName, otherLayerName)
docs: Assign **layerName** to the layer currently named
          **otherLayerName** and assign the name **otherLayerName**
          to the layer currently named **layerName**.
  
              >>> font.swapLayerNames("before drawing revisions", "after drawing revisions")