KeyRange.bound(lower, upper, [ bool lowerOpen = false, bool upperOpen = false ])

Source 

@DomName('KeyRange.bound')
factory KeyRange.bound(/*Key*/ lower, /*Key*/ upper,
        [bool lowerOpen = false, bool upperOpen = false]) =>
    _KeyRangeFactoryProvider.createKeyRange_bound(
        lower, upper, lowerOpen, upperOpen);