-`p1Style` : The end-cap style of the point `p1`. The value must be `"CAP_BUTT"`, `"CAP_SQUARE"` or `"CAP_ROUND"`. The default value is `"CAP_SQUARE"`.
-`p2Style` : The end-cap style of the point `p2`. The value must be `"CAP_BUTT"`, `"CAP_SQUARE"` or `"CAP_ROUND"`. The default value is `"CAP_SQUARE"`.
-`round_fn` : When the end-cap style is `"CAP_ROUND"`, it controlls the `$fn` value used by the `circle` module. The default value is `24`.