anchor.diff:  with the link.
   
   Some span nodes (like emphasis) can contain other formatting, so we need to recursively
  -process children. This is done by matching againts `Matching.SpanNodes` which is an active
  +process children. This is done by matching against `Matching.SpanNodes` which is an active
   pattern that recognizes any node with children. The library also provides a _function_
   named `Matching.SpanNode` that can be used to reconstruct the same node (when you want
   to transform document). This is similar to how the `ExprShape` module for working with 
  
positive.code: _direct_ link, code snippet and one more paragraph that includes an 
  _indirect_ link. The URLs of indirect links are defined by a separate
  block as demonstrated on the last line (and they can then be easily used repeatedly
  from multiple places in the documnet.
  
  Working with parsed documents
  -----------------------------
  
negative.code:   | _ -> ()
  
  (**
  You can find more detailed information about the document structure and how to process it
  in the book [F# Deep Dives](http://manning.com/petricek2/).
  
  Processing document recursively
  