Companion

Create a new empty A_BundleTree.

This is the LookupTreeAdaptor for building and navigating the ObjectSlots.LAZY_TYPE_FILTER_TREE_POJO. It gets built from 2-tuples containing a phrase type and a corresponding A_ParsingPlanInProgress. The type is used to perform type filtering after parsing each leaf argument, and the phrase type is the expected type of that latest argument.