Given a pango.attr_list.AttrList and callback function, removes any elements of list for which func returns true and inserts them into a new list.
callback function; returns true if an attribute should be filtered out
the new pango.attr_list.AttrList or null if no attributes of the given types were found
Given a pango.attr_list.AttrList and callback function, removes any elements of list for which func returns true and inserts them into a new list.