public static String toString(final BOp bop){
  final StringBuilder sb=new StringBuilder();
  toString(bop,sb,0);
  sb.setLength(sb.length() - 1);
  return sb.toString();
}

public static String toString ( final BOp bop ) { final StringBuilder sb = new StringBuilder ( ) ; toString ( bop , sb , 0 ) ; sb . setLength ( sb . length ( ) - 1 ) ; return sb . toString ( ) ; }
pretty print a bop .
