Drawing thick gizmo lines

The Unity gizmos DrawLine(...) method only draws lines that are a single pixel in width. For 3D projects, this can be hard to see. In the Unity forums, in March 2019, Jozard kindly suggested the following method to draw multiple single-pixel lines to create lines of greater thickness that are easier to see. Here is the updated code to do this:

void OnDrawGizmos (){
    ... (as before) 

    // draw thick lines ...
    DrawThickLine(top_right, bottom_right, 5);
    DrawThickLine(bottom_right, bottom_left, 5);
    DrawThickLine(bottom_left, top_left, 5);
    DrawThickLine(top_left, top_right, 5);

}

// from
// https://answers.unity.com/questions/1139985/gizmosdrawline-thickens.html
public static void DrawThickLine(Vector3 p1, Vector3 p2, float width)
{
    int count = 1 + Mathf.CeilToInt(width); // how many lines are needed.
    if (count == 1)
    {
        Gizmos.DrawLine(p1, p2);
    }
    else
    {
        Camera c = Camera.current;
        if (c == null)
        {
   ...