How to animate a row in Flutter?

Question

I have a row with width 200.0. It accepts lists with different lengths. Widgets in a list are always sized to take up the whole width of the row (width/list.length). List1 has 7 widgets, list2 has 4 widgets. How can I animate the transition between the lists, so that the widgets from the old list fade out and dissappear from left to right (7 - 4 = 3; 3 widgets must fade out and disspaear)? At the same time, the remaining 4 widgets must now take up the whole width and animate (width, color and position) from old to new values? I can't use any packages.