public boolean delete (String substring)
public XStringBuffer delete (int start, int end) throws StringIndexOutOfBoundsException
    public boolean delete (String substring)    {        int      i;        boolean  deleted = false;        i = buf.toString().indexOf (substring);        if (i > -1)        {            buf.delete (i, i + substring.length());            deleted = true;        }        return deleted;    }