code: function smoothCurveRadius(x1, y1, x2, y2) {
      const dx = x2 - x1;
      const dy = y2 - y1;
  
      return Math.sqrt(dx * dx + dy * dy);
  }
docs: Computes radius for a smooth curve effect.
  @param {number} x1 - x value for point 1
  @param {number} y1 - y value for point 1
  @param {number} x2 - y value for point 2
  @param {number} y2 - y value for point 2
  @returns{number} value of radius.
  @memberof Link/helper