anchor.diff:  
   [source,java]
   ----
  -UriActionCommand command = mapperTree.interpretFragment("/helloWorld");
  +UriActionCommand command = mapperTree.interpretFragment("helloWorld");
   ----
   
   This will trigger the interpretation process during which the URI fragment is disassembled and resolved to a URI action command class. The action mapper tree will resolve this fragment to the class object provided by us during the construction of the mapper tree: `HelloWorldActionCommand`. It will then create an instance of this class, execute it and return the command object as a result.
  
positive.code: 
  We have now defined a hierarchy of URI action mappers which consists of sub-tree mappers and simple mappers for the hierarchy's leaf nodes. Next, we want to add parameters to this hierarchy. We can add parameters to every level of the action mapper tree. The library provides a number of predefined URI parameter classes that can be used out of the box. If these classes don't cover all of your use cases, you can easily write your own parameter classes. This is described in a later section.
  
  === Parameter Names and Parameter Identifier
  
  As we have learned previously, URI fragment parameters can be single-valued or multi-valued. Regardless of the number of individual values a parameter is composed of, a parameter is always represented by a class which implements the `org.roklib.urifragmentrouting.parameter.UriParameter` interface. In order to uniquely identify a parameter, a parameter object needs to be instantiated with a unique identifier. Besides this id, a URI fragment parameter has to be given one parameter name per individual parameter value.
  
  
negative.code: 
  As you can see, after we called `finishMapper()` the builder is reset to the root of the mapper tree and we can go on adding the next sibling path segment to be handled by the mapper tree.
  
  == Adding Hierarchy [[hierarchy]]
  
  Next we want to add some hierarchy to the mapper tree. We would now like to be able to interpret the following URI fragments:
  
  ....
  #!user
  #!user/profile
  #!admin
  #!admin/users
  #!admin/groups
  #!settings
  ....
  
  We will do this in a depth-first manner:
  