def write_json_escape_char(ch)
      trans.write('\\u')
      ch_value = ch[0]
      if (ch_value.kind_of? String)
        ch_value = ch.bytes.first
      end
      trans.write(ch_value.to_s(16).rjust(4,'0'))
    end
def write_json_escape_char(ch)
      trans.write('\\u')
      ch_value = ch[0]
      if (ch_value.kind_of? String)
        ch_value = ch.bytes.first
      end
      trans.write(ch_value.to_s(16).rjust(4,'0'))
    end
Write the character ch as a JSON escape sequence ("\u00xx")