copy
Returns this object rebuilt around the replacement geometry circle — the hook the shape-preserving operations return through.
Every operation that moves a circle computes its result as a plain Circle and returns it through this hook. This base implementation returns circle itself; a subclass overrides it to rebuild an instance of its own class around circle, and every such operation then comes back as that class. The result's runtime class must equal the receiver's — the operations check it and fail with a named error when a subclass misses the override.
Return
circle itself; an override returns its own class rebuilt around circle.
Parameters
circle
The replacement geometry.