using System;
using System.Collections.Generic;

public class NaturalComparer[T] : IComparer[T]
  where T: IComparable[T]
{
  public Compare (mutable  a : T,mutable  b :  T) :  int
  {
     a.CompareTo (b);
  }
}

public class X
{
  class Test : IComparable[Test]
  {
    public CompareTo (mutable  _that : Test) :  int
    {
       0;
    }

    public Equals (mutable  _that : Test) :  bool
    {
       false;
    }
  }

  static Main () :  void
  {
    mutable  cmp =  NaturalComparer ();
    mutable  a =  Test ();
    mutable  b =  Test ();
    _ = cmp.Compare (a, b);
  }
}
/*
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*/