Set<String> (@NotNull PyArgumentList node) { final Set<String> keywordArgumentNames = new HashSet<>(); final Set<String> results = new HashSet<>(); for (PyExpression argument : node.getArguments()) { if (argument instanceof PyKeywordArgument) { final String keyword = ((PyKeywordArgument)argument).getKeyword(); if (keywordArgumentNames.contains(keyword)) { results.add(keyword); } keywordArgumentNames.add(keyword); } } return results; }