public SourceRange cspCatchers(List<JCCatch> trees) {
            if ((trees == null) || !(trees.nonEmpty())) return null;
            SourceRange list_sr = new SourceRange();
            for (List<JCCatch> l = trees; l.nonEmpty(); l = l.tail) {
                list_sr.mergeWith(csp(l.head));
            }
            positions.put(trees, list_sr);
            return list_sr;
        }