public <T extends JCTree>void printExprs(List<T> trees,String sep) throws IOException {
  if (trees.nonEmpty()) {
    printExpr(trees.head);
    for (List<T> l=trees.tail; l.nonEmpty(); l=l.tail) {
      print(sep);
      if (sep.endsWith("\n")) {
        align();
      }
      printExpr(l.head);
    }
  }
}

public < T extends JCTree > void printExprs ( List < T > trees , String sep ) throws IOException { if ( trees . nonEmpty ( ) ) { printExpr ( trees . head ) ; for ( List < T > l = trees . tail ; l . nonEmpty ( ) ; l = l . tail ) { print ( sep ) ; if ( sep . endsWith ( "\n" ) ) { align ( ) ; } printExpr ( l . head ) ; } } }
derived visitor method : print list of expression trees , separated by given string .
