anchor.diff:  It takes a sample document as an input (or document containing a root XML node with
   multiple child nodes that are used as samples). The generated type can then be used 
   to read files with the same structure. If the loaded file does not match the structure 
  -of the sample, an exception may occur (but only when accessing e.g. non-existing element).
  +of the sample, an runtime error may occur (but only when accessing e.g. non-existing element).
   
   ## Introducing the provider
   
  
positive.code: 
  ### Types for more complex structure
  
  Let's now look at a number of examples that have more interesting structure. First of 
  all, what if a node contains some value, but also has some attributes?
  *)
  
  
negative.code: type Rss = XmlProvider<"http://tomasp.net/blog/rss.aspx">
  
  (**
  This code builds a type `Rss` that represents RSS feeds (with the features that are used
  on `http://tomasp.net`). The type `Rss` provides static methods `Parse` and `Load`
  to construct it - here, we just want to reuse the same uri of the schema, so we
  use the `GetSample` static method:
  