<PackageReference Include="NETStandard.Library" Version="2.0.2" />

System.ValueTuple<T1, T2>

namespace System { public struct ValueTuple<T1, T2> : IStructuralComparable, IStructuralEquatable, IComparable, IComparable<(T1, T2)>, IEquatable<(T1, T2)> { public T1 Item1; public T2 Item2; public ValueTuple(T1 item1, T2 item2); public int CompareTo((T1, T2) other); public bool Equals((T1, T2) other); } }