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