ReadonlyIndex0 for the base, then one per {% if %} in source order.
ReadonlyOverridesThe values that differ from the base assignment; empty for the base.
ReadonlySatisfiableWhether parameter values can make the toggled block take another branch. false when its
conditions read loop values, filtered values or Context comparisons, or when no tried
assignment worked; such a variant has no overrides and renders like the base.
ReadonlyToggleThe {% if %} this variant toggles; null for the base.
One render of the template: the base assignment with some values overridden.