def ns_left_fin
import bend-collections@1.0.0.0/src/containers/balanced_search_tree.bend as BalancedSearchTreeimport Base
138def ns_left_fin(~K: Data, +limit: Nat, +depth: Nat, +cap: Nat, +used: Nat, tags: Array<Nat>, rights: Array<Nat>, parents: Array<Nat>, keys: Array<Maybe<&2, K>>, q: Array<Nat> & Nat) -> NodeStore<K> & Nat:
139 (lefts, +x) = q
140 (NS{limit, depth, cap, used, tags, lefts, rights, parents, keys}, x)