class Test

	def main
		assert .square(5)==25
		expect RequireException, .square(0)

		.useForExpr(['foo', 'foo'])
		expect RequireException, .useForExpr(['foo', 'bar'])

		.useChainedComparison(5)
		expect RequireException, .useChainedComparison(-1)
		expect RequireException, .useChainedComparison(10)

	def square(x as int) as int
		require
			x > 0
		body
			return x*x

	def useForExpr(t as List<of String>)
		require
			all for s in t get s == 'foo'
		body
			pass

	def useChainedComparison(i as int)
		require
			0 <= i < 10
		body
			pass