def clockwise?
	    edges.map {|e| (e.last.x - e.first.x) * (e.last.y + e.first.y)}.reduce(:+) >= 0
	end
def clockwise?
	    edges.map {|e| (e.last.x - e.first.x) * (e.last.y + e.first.y)}.reduce(:+) >= 0
	end
Check the orientation of the {Polygon}
 @return [Boolean] True if the {Polygon} is clockwise, otherwise false