EdgeInsets.symmetric constructor Null safety

const EdgeInsets.symmetric(
  1. {double vertical = 0.0,
  2. double horizontal = 0.0}
)

Creates insets with symmetrical vertical and horizontal offsets.

link
Eight pixel margin above and below, no horizontal margins: 
const EdgeInsets.symmetric(vertical: 8.0)

Implementation

const EdgeInsets.symmetric({
  double vertical = 0.0,
  double horizontal = 0.0,
}) : left = horizontal,
     top = vertical,
     right = horizontal,
     bottom = vertical;