# File lib_core/rucy/message.rb, line 48
    def set_header(name, value, append=false)
      normalized_name = Message.normalize_header(name)
      if (value_list = @header[normalized_name]) then
        if (append) then
          value_list.push(value)
        else
          value_list[0] = value
        end
      else
        @header[normalized_name] = [ value ]
      end

      nil
    end