code: private void addToCurrentChainList(String line) {
  		int index = line.indexOf(":");
  		String chainList = line.substring(index+1).trim();
  		// split by spaces or commas
  		String[] chainIds = chainList.split("[ ,]+");
  		currentChainIDs.addAll(Arrays.asList(chainIds));
  	}
docs: Parses list of chain ids (A, B, C, etc.)