anchor.diff:    ; e.g. to translate NIL to "false" and T to "true".
     (symbol-translations      nil)
   
  -  ; Defined CLASSes.
  -  (defined-classes          (make-hash-table :test #'eq))
  -
  -  (late-symbols             (make-hash-table :test #'eq))
     (exported-closures        nil)
     (delayed-exprs            nil)
     (memorized-sources        nil)
  
positive.code:   (+! (delayed-exprs) (frontend (list x)))
    nil)
  
  (fn add-late-symbol (x)
    (= (href (late-symbols) x) t)
    x)
  
  (fn add-toplevel-expression (x)
    (push x (accumulated-toplevel-expressions)))
  
  
negative.code: (transpiler-getter-not-global function-body      (cdr (transpiler-defined-function tr x)))
  (transpiler-getter wanted-function?        (href (transpiler-wanted-functions-hash tr) x))
  (transpiler-getter wanted-variable?        (href (transpiler-wanted-variables-hash tr) x))
  
  (transpiler-getter add-defined-variable  (= (href (transpiler-defined-variables tr) x) t)
                                           x)
  