Path.curve_() method draws a cubic Bézier curve from the current position
via two control points to a given endpoint. However, the end control point is
identical to the end point.
Path path.curve_(Point cp1, Point to)
This method is chainable as it returns the
The main purpose of this method is to save your some typing, as the two following calls yield the same result:
.curve(point1, point2, point2) .curve_(point1, point2)