672 		layerNames = [layerName for layerName, directoryName in layerContents]
685 		for layerName, layerDirectory in layerContents:
687 				return layerName
691 	def getGlyphSet(self, layerName=None, validateRead=None, validateWrite=None):  argument
694 		glyphs directory mapped to layerName
695 		in the UFO. If layerName is not provided,
710 		if layerName is None:
711 			layerName = self.getDefaultLayerName(validate=validateRead)
715 			if layerName == storedLayerName:
719 			raise UFOLibError("No glyphs directory is mapped to \"%s\"." % layerName)
724 				f"No '{directory}' directory for layer '{layerName}'"
734 	def getCharacterMapping(self, layerName=None, validate=None):  argument
741 		glyphSet = self.getGlyphSet(layerName, validateRead=validate, validateWrite=True)
1406 			for layerName in layerOrder:
1407 				if layerName is None:
1408 					layerName = DEFAULT_LAYER_NAME
1409 				newOrder.append(layerName)
1415 		layerContents = [(layerName, self.layerContents[layerName]) for layerName in layerOrder]
1418 	def _findDirectoryForLayerName(self, layerName):  argument
1421 			if layerName is None and directoryName == DEFAULT_GLYPHS_DIRNAME:
1424 			elif existingLayerName == layerName:
1428 			raise UFOLibError("Could not locate a glyph set directory for the layer named %s." % layerName)
1433 		layerName=None,  argument
1443 		If layerName is None, the default glyph set
1464 			and (not defaultLayer or layerName is not None)
1470 		if layerName is None and defaultLayer:
1473 					layerName = existingLayerName
1474 			if layerName is None:
1475 				layerName = DEFAULT_LAYER_NAME
1476 		elif layerName is None and not defaultLayer:
1490 				layerName=layerName,
1521 		layerName=None,  argument
1534 					if existingLayerName != layerName:
1539 				elif existingLayerName == layerName:
1542 		if layerName in self.layerContents:
1543 			directory = self.layerContents[layerName]
1552 				directory = userNameToFileName(layerName, existing=existing, prefix="glyphs.")
1556 		self.layerContents[layerName] = directory
1567 	def renameGlyphSet(self, layerName, newLayerName, defaultLayer=False):  argument
1572 		layerName, it is up to the caller to inform that object that
1581 		if layerName == newLayerName:
1583 			if self.layerContents[layerName] != DEFAULT_GLYPHS_DIRNAME and not defaultLayer:
1586 			if self.layerContents[layerName] == DEFAULT_GLYPHS_DIRNAME and defaultLayer:
1598 		oldDirectory = self._findDirectoryForLayerName(layerName)
1605 		del self.layerContents[layerName]
1610 	def deleteGlyphSet(self, layerName):  argument
1612 		Remove the glyph set matching layerName.
1618 		foundDirectory = self._findDirectoryForLayerName(layerName)
1620 		del self.layerContents[layerName]