code: public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
    {
  
      String theFirstString = m_arg0.execute(xctxt).str();
      String theSecondString = m_arg1.execute(xctxt).str();
      String theThirdString = m_arg2.execute(xctxt).str();
      int theFirstStringLength = theFirstString.length();
      int theThirdStringLength = theThirdString.length();
  
      // A vector to contain the new characters.  We'll use it to construct
      // the result string.
      StringBuffer sbuffer = new StringBuffer();
  
      for (int i = 0; i < theFirstStringLength; i++)
      {
        char theCurrentChar = theFirstString.charAt(i);
        int theIndex = theSecondString.indexOf(theCurrentChar);
  
        if (theIndex < 0)
        {
  
          // Didn't find the character in the second string, so it
          // is not translated.
          sbuffer.append(theCurrentChar);
        }
        else if (theIndex < theThirdStringLength)
        {
  
          // OK, there's a corresponding character in the
          // third string, so do the translation...
          sbuffer.append(theThirdString.charAt(theIndex));
        }
        else
        {
  
          // There's no corresponding character in the
          // third string, since it's shorter than the
          // second string.  In this case, the character
          // is removed from the output string, so don't
          // do anything.
        }
      }
  
      return new XString(sbuffer.toString());
    }
docs: Execute the function.  The function must return
  a valid object.
  @param xctxt The current execution context.
  @return A valid XObject.
  
  @throws javax.xml.transform.TransformerException