Hero({Key key, @required Object tag, int turns: 1, bool alwaysAnimate: false, @required Widget child })

Create a hero.

The tag and child are required.

Source 

Hero({
  Key key,
  @required this.tag,
  this.turns: 1,
  this.alwaysAnimate: false,
  @required this.child,
}) : super(key: key) {
  assert(tag != null);
  assert(turns != null);
  assert(alwaysAnimate != null);
  assert(child != null);
}