code: def validate!
        banner! if @argv.flag?('help')
        unless @argv.empty?
          argument = @argv.remainder.first
          help! ArgumentSuggester.new(argument, self.class).suggestion
        end
        help! if self.class.abstract_command?
      end
docs: Raises a Help exception if the `--help` option is specified, if `argv`
   still contains remaining arguments/options by the time it reaches this
   implementation, or when called on an ‘abstract command’.
  
   Subclasses should call `super` _before_ doing their own validation. This
   way when the user specifies the `--help` flag a help banner is shown,
   instead of possible actual validation errors.
  
   @raise [Help]
  
   @return [void]