def begin_contour():
    """
	Use the beginContour() and endContour() functions 
	to create negative shapes within shapes such as 
	the center of the letter 'O'. beginContour() begins 
	recording vertices for the shape and endContour() stops 
	recording. The vertices that define a negative shape must 
	"wind" in the opposite direction from the exterior shape. 
	First draw vertices for the exterior clockwise order, then 
	for internal shapes, draw vertices shape in counter-clockwise. 

	"""
    global is_contour, contour_vertices, contour_vertices_types
    is_contour = True
    contour_vertices = []
    contour_vertices_types = []
