def add_param(type, val)
      type = type.chr if type.is_a?(Integer)
      @signature += type.to_s
      @params << [type, val]
    end
def add_param(type, val)
      type = type.chr if type.is_a?(Integer)
      @signature += type.to_s
      @params << [type, val]
    end
Add a parameter _val_ of type _type_ to the message.