Complex sentence: Swinger girl is constant in her attempts to swing over the top of the swing set, staying late one day Spinelli believes she has seen swinger girl finally reach this goal and disappear into a flash of light.
Split into simpler sentences: Swinger Girl is constant in her attempts to swing over the top of the swing set. Staying late one day, Spinelli believes she has seen Swinger Girl finally reach this goal and disappear into a flash of light.