public enum ProductEnum
{
  INSTANCE
}
public static class ProductEnumExtensions
{
  private static int state = 0;
  public static void DoSomething(this ProductEnum it) {
    System.Console.WriteLine("I did something for the {0} time", ++state);
  }
}

public enum ProductEnum
{
  INSTANCE
}
public static class ProductEnumExtensions
{
  private static int state = 0;
  public static void DoSomething(this ProductEnum it) {
    System.Console.WriteLine("I did something for the {0} time", ++state);
  }
}

public enum SingletonEnum {
    INSTANCE;

    int value;

    public int getValue() {
        return value;
    }

    public void setValue(int value) {
        this.value = value;
    }
}

public enum SingletonEnum {
    INSTANCE;

    int value;

    public int getValue() {
        return value;
    }

    public void setValue(int value) {
        this.value = value;
    }
}

public class NoDI
{
    private readonly IServiceOne _serviceOne;
    private readonly IServiceTwo _serviceTwo;
    
    public NoDI()
    {
        _serviceOne = new ServiceOne(); // ServiceOne that I need to re-use
        _serviceTwo = new ServiceTwo();
        _serviceTwo2 = new ServiceTwo(); // want ServiceTwo to be new every time
    }
}

public class NoDI
{
    private readonly IServiceOne _serviceOne;
    private readonly IServiceTwo _serviceTwo;
    
    public NoDI()
    {
        _serviceOne = new ServiceOne(); // ServiceOne that I need to re-use
        _serviceTwo = new ServiceTwo();
        _serviceTwo2 = new ServiceTwo(); // want ServiceTwo to be new every time
    }
}

C#
<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

</Project>

C#
<Project Sdk="Microsoft.NET.Sdk.Web">

  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <Nullable>enable</Nullable>
    <ImplicitUsings>enable</ImplicitUsings>
  </PropertyGroup>

</Project>