# File lib_core/rucy/message.rb, line 80
    def delete_header_if(name)
      deleted = false
      normalized_name = Message.normalize_header(name)
      if (value_list = @header[normalized_name]) then
        value_list.delete_if{ |value|
          if (yield(value)) then
            deleted = true
          end
        }
      end

      deleted ? self : nil
    end