anchor.diff:  
   
   (defun id (x)
  -  "Return the value X unmodified."
  +  "Return the value X unmodified.
  +
  +   ### Example
  +   ```cl
  +   > (map id '(1 2 3))
  +   out = (1 2 3)
  +   ```"
     x)
   
   (defun as-is (x)
  -  "Return the value X unchanged."
  +  "Return the value X unchanged.
  +
  +   ### Example
  +   ```cl
  +   > (map as-is '(1 2 3))
  +   out = (1 2 3)
  +   ```"
     x)
   
   (defun const (x)
  
positive.code:   (lambda () x))
  
  (defun call (x key &args)
    "Index X with KEY and invoke the resulting function with ARGS."
    (apply (.> x key) args))
  
  (defun self (x key &args)
    "Index X with KEY and invoke the resulting function with X and ARGS."
    (apply (.> x key) x args))
  
negative.code: 
  (defun slot? (symb)
    "Test whether SYMB is a slot. For this, it must be a symbol, whose
     contents are `<>`.
  
     ### Example
     ```cl
     > (slot? '<>)
     out = true
     > (slot? 'not-a-slot)
     out = false
     ```"
    (and (symbol? symb) (= (.> symb "contents") "<>")))
  
  (defmacro cut (&func)
  