Zwei Punkte dart
.. is known as cascade notation.
It allows you to not repeat the same target if you want to call several methods on the same object.
List list = [];
list.add(color1);
list.add(color2);
list.add(color3);
list.add(color4);
// with cascade
List list = [];
list
..add(color1)
..add(color2)
..add(color3)
..add(color4);
Successful Sardine