static closeTo(val, maxDelta = 0.000001) {
    const E = /** @type {number} */(maxDelta);
    return /** @type {number} */(/** @type {?} */({
      asymmetricMatch: (other) => other >= val - E && other <= val + E,
      jasmineToString: () => '<closeTo: ' + val + '>',
    }));
  }
Creates a custom matcher object that matches a number that is close to the
given value.

@param {number} val
@param {number=} maxDelta
@return {number}