def contexts(self):
        """ Returns a set of all contexts in this list. """
        result = set()
        for todo in self._todos:
            contexts = todo.contexts()
            result = result.union(contexts)

        return result
def contexts ( self ) : result = set ( ) for todo in self . _todos : contexts = todo . contexts ( ) result = result . union ( contexts ) return result
Returns a set of all contexts in this list.