namespace System
{
    public readonly struct Int64 : IComparable, IComparable<long>, IConvertible, IEquatable<long>, IFormattable, IParsable<long>, ISpanFormattable, ISpanParsable<long>, IUtf8SpanFormattable, IUtf8SpanParsable<long>, IAdditionOperators<long, long, long>, IAdditiveIdentity<long, long>, IBinaryInteger<long>, IBinaryNumber<long>, IBitwiseOperators<long, long, long>, IComparisonOperators<long, long, bool>, IDecrementOperators<long>, IDivisionOperators<long, long, long>, IEqualityOperators<long, long, bool>, IIncrementOperators<long>, IMinMaxValue<long>, IModulusOperators<long, long, long>, IMultiplicativeIdentity<long, long>, IMultiplyOperators<long, long, long>, INumber<long>, INumberBase<long>, IShiftOperators<long, int, long>, ISignedNumber<long>, ISubtractionOperators<long, long, long>, IUnaryNegationOperators<long, long>, IUnaryPlusOperators<long, long>
    {
        public static long PopCount(long value);
    }
}