Gap constructor
Creates a widget that takes a fixed mainAxisExtent
of space in the
direction of its parent.
The mainAxisExtent
must not be null and must be positive.
The crossAxisExtent
must be either null or positive.
Implementation
const Gap(
this.mainAxisExtent, {
Key? key,
this.crossAxisExtent,
this.color,
}) : assert(mainAxisExtent >= 0 && mainAxisExtent < double.infinity),
assert(crossAxisExtent == null || crossAxisExtent >= 0),
super(key: key);