BorderRadius.horizontal constructor

const BorderRadius.horizontal({Radius left: Radius.zero, Radius right: Radius.zero })

Creates a horizontally symmetrical border radius where the left and right sides of the rectangle have the same radii.

Implementation 

const BorderRadius.horizontal({
  Radius left = Radius.zero,
  Radius right = Radius.zero,
}) : this.only(
  topLeft: left,
  topRight: right,
  bottomLeft: left,
  bottomRight: right,
);