code: def normalize_item(self, value=_nothing, coll=None, index=None):
          
          if value is not _nothing and hasattr(coll, "compare_item_as"):
              value = coll.compare_item_as(value)
          return self.normalize_val(value)
docs: Hook which is called on every *collection item*; this is a way to
          perform context-aware clean-ups.
  
          args:
  
              ``value=``\ *nothing*\ \|\ *anything*
                  The value in the collection slot.  *nothing* can be detected in
                  sub-class methods as ``self._nothing``.
  
              ``coll=``\ *COLLECTION*
                  The parent :py:class:`normalize.coll.Collection` instance.  If
                  this instance has a ``compare_item_as`` method, then that
                  method is called to perform a clean-up before the value is
                  passed to ``normalize_val``
  
              ``index=``\ *HASHABLE*
                  The key of the item in the collection.