docs: def rename_pickled_ontology(filename, newname):
  	""" try to rename a cached ontology """
  	pickledfile = ONTOSPY_LOCAL_CACHE + "/" + filename + ".pickle"
  	newpickledfile = ONTOSPY_LOCAL_CACHE + "/" + newname + ".pickle"
  	if os.path.isfile(pickledfile) and not GLOBAL_DISABLE_CACHE:
  		os.rename(pickledfile, newpickledfile)
  		return True
  	else:
  		return None