anchor.diff:  <template class="<component-class>"
             combination="<template-combination>">
      ...
  -   <sub-template/>
  +   <next-template/>
   </template>
   
   Examples:
   
  -We may want to have :above (equivalent to :before), :below (equivalent to :after) and :around. Besides, we can embed other templates (in the case of subclassing or :around method combinations, for example) using the special XML element <sub-template/>
  +We may want to have :above (equivalent to :before), :below (equivalent to :after) and :around. Besides, we can embed other templates (in the case of subclassing or :around method combinations, for example) using the special XML element <next-template/>
   
   <template class="object-editor"
             combination="above">
  
positive.code: <template class="object-editor"
            combination="around">
     <container id="object-name"/>
     <sub-template/>
     <container id="accept-action"/>
     <container id="cancel-action"/>
  </template>
  
  Besides, it also makes sense to use <sub-template/> outside and :around template-combination. It is the equivalent of call-next-method
  
  The following model (imagine the corresponding components...):
  (defclass person ()
  
negative.code:   <container id="lastname"/>
  </template>
  
  Finally, it is not clear to me whether the following is correct or not, but we could give more controls to templates throw some calculation, although I think EVERY calculation should be in the controller, so...
  
  We could have some expressions that expand to dataflow cells:
  
  <template class="person-viewer">
    <container id="name"/>
    <container id="lastname"/>
    <div class="age">
      <formula f="(+1 (age comp))"/>
    </div>
  </template>
  
  (+1 (age comp)) should expand to something like:
  
  (make-formula :formula (lambda ()
  			 (+1 (age comp)))) and compiled in an environment where comp makes sense
  
  
  
  
  |#