Unified, remark là các processor
Every processor implements another processor. To create a processor, call another processor. The new processor is configured to work the same as its ancestor. But when the descendant processor is configured in the future it does not affect the ancestral processor.
When processors are exposed from a module (for example, unified itself) they should not be configured directly, as that would change their behavior for all module users. Those processors are frozen and they should be called to create a new processor before they are used.