#{
	sum <- :l {
		l fold: 0 with: :acc el {
			acc + el
		}
	}
	main <- {
		print: (string: (sum: [])) . "\n"
		print: (string: (sum: [1 2 3 4])) . "\n"
		print: (string: (sum: 1 | 2 | 3 | 4 | [])) . "\n"
		print: (string: (sum: [1 2] . [3 4])) . "\n"
	}
}