New in version 2.0.
Iterate scores forward in expr:
abjad> score_1 = Score([Staff("c'8 d'8 e'8 f'8")])
abjad> score_2 = Score([Staff("c'1"), Staff("g'1")])
abjad> scores = [score_1, score_2]
abjad> for score in scoretools.iterate_scores_forward_in_expr(scores):
... score
Score<<1>>
Score<<2>>
Ignore threads.
Return generator.