anchor.diff:  (defpass inline (state nodes usage)
     "Inline simple functions."
     :cat '("opt" "usage")
  +  :on false
     (with (score-lookup (empty-struct))
       (visitor/visit-block nodes 1
         (lambda (node)
  
positive.code: (import urn/analysis/pass ())
  (import urn/analysis/usage usage)
  (import urn/analysis/visitor visitor)
  
  (import lua/math math)
  
  (define scope/child :hidden (.> (require "tacky.analysis.scope") :child))
  (define scope/add! :hidden (.> (require "tacky.analysis.scope") :add))
  
negative.code:     sum
      (with (score (score-node (nth nodes start)))
        (if score
          (if (> score threshold)
            score
            (score-nodes nodes (succ start) (+ sum score)))
          false))))
  
  (define threshold
  