head_color(type:color.T)default="The color of the arrow head.".
head_style(type:int)default="The value of 0 draws a triangular arrow head. The value of 1 draws a swallow-tail arrow head. The value of 2 draws a circular head. The value of 3 draws a diamond-shaped head.".
head_len(type:lengthinpoints(\\xref{unit}))default="The length of the arrow head.".