or type
    >npm install
    >npm start

//the constructor takes the id of the 
//parent element and draws the calendar inside
	const calendar = new Calendar('calendar-wrap')

//set the date of the calendar you want
	calendar.setDateTo(next_date)

//redraw calendar to the next month
	calendar.moveRight()

//redraw to the prev month
	calendar.moveLeft()

//get the date the user has chosen
	calendar.selected_date