def append(cls, d, s, filter=Filter()):
        """
        Append schema object's from B{s}ource list to
        the B{d}estination list while applying the filter.
        @param d: The destination list.
        @type d: list
        @param s: The source list.
        @type s: list
        @param filter: A filter that allows items to be appended.
        @type filter: L{Filter}
        """
        for item in s:
            if item in filter:
                d.append(item)
Append schema object's from B{s}ource list to
        the B{d}estination list while applying the filter.
        @param d: The destination list.
        @type d: list
        @param s: The source list.
        @type s: list
        @param filter: A filter that allows items to be appended.
        @type filter: L{Filter}