operator [] method
The object at the given index in the list.
The index must be a valid index of this list,
which means that index must be non-negative and
less than length.
Implementation
@override
bool operator [](int index) {
RangeError.checkValidIndex(index, this, 'index', _length);
return (_data[index >> _entryShift] &
(1 << (index & _entrySignBitIndex))) !=
0;
}