NewProcessor returns a new Processor instance with the default settings.

NullProcessCallback is the default ProcessCallback; it just returns nil.

Process the given value recursively using the default options.

Processor holds the state for a process run.

ZGrabTag holds the information from the `zgrab` tag.

ProcessCallback is called for each element in a struct; if it returns a non-nil value, that value will be used and further processing on that element will be skipped.