docs: public static double overlap(double x1, double x2, double x3, double x4) {
          if (x3 < x1) {
              if (x4 < x1) {
                  return 0;
              } else {
                  return Math.min(x2, x4) - x1;
              }
          } else {
              if (x2 < x3) {
                  return 0;
              } else {
                  return Math.min(x2, x4) - x3;
              }
          }
      }