docs: function sameValue(x, y) {
          if (x === y) {
              // 0 === -0, but they are not identical
              return x !== 0 || 1 / x === 1 / y;
          }
  
          // NaN !== NaN, but they are identical.
          // NaNs are the only non-reflexive value, i.e., if x !== x,
          // then x is a NaN.
          // isNaN is broken: it converts its argument to number, so
          // isNaN('foo') => true
          return x !== x && y !== y;
      }