'update the collection /w header value (may have side effects)
This method is similar to ``update`` only that usage may result
in other headers being changed as recommended by the corresponding
specification.  The return value is defined by the particular
sub-class. For example, the ``_CacheControl.apply()`` sets the
``Expires`` header in addition to its normal behavior.'

def apply(self, collection, **kwargs):

    self.update(collection, **kwargs)
