code: public static void appendPair(StringBuffer b, String s1, String s2,
                                    String separator, String terminator) {
  
          b.append(s1);
          b.append(separator);
          b.append(s2);
          b.append(terminator);
      }
docs: Appends a pair of string to the string buffer, using the separator between
  and terminator at the end
  @param b the buffer
  @param s1 first string
  @param s2 second string
  @param separator separator string
  @param terminator terminator string