function Span(a, b, center) {
      this.isArray = void 0;
      this.a = void 0;
      this.b = void 0;
      this.center = void 0;
      if (Util.isArray(a)) {
        this.isArray = true;
        this.a = a;
      } else {
        this.isArray = false;
        this.a = Util.initValue(a, 1);
        this.b = Util.initValue(b, this.a);
        this.center = Util.initValue(center, false);
      }
    }
Creates a new Span instance.
@param {number|number[]} a - The first value or an array of values.
@param {number} [b] - The second value (if a is not an array).
@param {boolean} [center=false] - Whether to use center-based calculation.