margin method
Implementation
Container margin({double left = 0, double top = 0, double right = 0, double bottom = 0, vertical, horizontal}) => Container(
margin: vertical != null || horizontal != null ? EdgeInsets.symmetric(vertical: vertical ?? 0, horizontal: horizontal ?? 0) : EdgeInsets.only(left: left, top: top, right: right, bottom: bottom),
child: this,
);