// This is a modified excerpt from Flutter library source code

// We have a class called EdgeInsets

class EdgeInsets extends EdgeInsetsGeometry {
//   The first constructor
  const EdgeInsets.fromLTRB(this.left, this.top, this.right, this.bottom);
//   The second constrctor
//   Notice: There's a colon following the signature, which resembles the form in C++
  const EdgeInsets.all(double value)
    : left = value,
      top = value,
      right = value,
      bottom = value;
//   The third constructor
//   Notice: how named arguments are used
  const EdgeInsets.only({
    this.left = 0.0,
    this.top = 0.0,
    this.right = 0.0,
    this.bottom = 0.0,
  });
//   .....
}