anchor.diff:    ... (please this inc :counter) ...) ;;<3>
   
   ;; test file
  +(:require
  +  [untangled-spec.core :refer [when-mocking assertions])
  +
   (when-mocking
     (please this f x) => (do ...) ;;<4>
     (assertions
  
positive.code: 
  [source]
  ----
  (assertions
    actual => expected ;;<1>
    actual =fn=> expected ;;<2>
  
negative.code: 
  [source]
  ----
  (:require
    [untangled-spec.core :refer [when-mocking assertions])
  
  (let [real-fn f]
    (when-mocking f => (do ... (real-fn))
    (assertions
  