CircularKernel::ConstructCircularSourceVertex_2

A model fo of this type must provide:

CircularKernel::Circular_arc_point_2
fo ( CircularKernel::Circular_arc_2 c )
Constructs the source vertex of c.

CircularKernel::Circular_arc_point_2
fo ( CircularKernel::Line_arc_2 l )
Same, for a line segment.