example.rb

if @messages = Message.all ## need to test for nil 
   @messages_in_last_week = messages_last_week ## move this out to a method
else
   @messages_in_last_week = false
end

def messages_last_week
  @messages_in_last_week = @messages.select { |m| m.created_at <= 7.days.ago } 
  @messages_in_last_week = false if @messages_in_last_week.empty? 
  ## bugs happen if the variable gets assigned [] in one place and false in another
end