def METHOD_NAME(values_file):
	'''Return the custom.profiles names from jupyterhub config values.'''
	if not os.path.exists(values_file):
		print(f"No such file: {values}")
		return
	values = yaml.load(open(values_file).read())
	if 'custom' not in values:
		print("No 'custom' in values.yaml.")
		return []
	if 'profiles' not in values['custom']:
		print("No 'custom.profiles' in values.yaml.")
		return []
	if not hasattr(values['custom']['profiles'], 'keys'):
		print("'custom.profiles' is not a dictionary.")
		return []
	return list(values['custom']['profiles'].keys())