state transitions cluster__composite composite cluster__composite_b b __initial _outer outer __initial->_outer _composite_history H _outer->_composite_history _composite_initial _composite_initial->_composite_b _composite_a a _composite_b_initial _composite_b_s2 s2 enter ^out.s2 _composite_b_initial->_composite_b_s2 _composite_b_s1 s1 enter ^out.s1