Having a probelm with a Struck constance, which wont allow me to create a calender : I am trying to create a calendar and have been following a tutorial on YouTube 'calendar ruby on rails' first video. once I inputted the code i had an error
'uninitialized constant CalenderHelper::Struck' <----- that is the error message

the code is;

module CalenderHelper
	def calender(date = Date.today, &block)
		Calender.new(self, date, block).table
	end
	
	**class Calender < Struck.new(:view, :date, :callback)**
		HEADER = %w[Sunday Monday Tuesday Wednesday Thursday Friday Saturday]
		START_DAY = :sunday	

		delegate :content_tag, to: :view

	def table
		content_tag :table, class: "calender" do
			header + week_rows
		end
	end

	def header
		content_tag :tr do
		HEADER.map { |day| content_tag :th, day }.join.html_safe
		end
	end

	def week_rows
		week.map do |week|
			content_tag :tr do
				week.map { |day| day_cell(day) }.join.html_safe
			end
		end.join.html_safe
	end

	def day_cell(day)
		content_tag :td, view.capture(day, &callback), class: day_classes(day)
	end

	def day_classes(day)
		classes = []
		classes << "today" if day == Date.today
		classes << "notmonth" if day.month != date.month
		classes.empty? ? nil : classes.join(" ")
	end
	
	def weeks 
		first = date.beginning_of_month.beginning_of_week(START_DAY)
		last = date.end_of_month.end_of_week(START_DAY)
		(first..last).to_a.in_groups_of(7)
		end
	end
end	

line with the error is marker with starts on each side