```c#
void Main()
{

	//ok
	var ComplexUser = new ComplexUser();
	var complex = ComplexUser.complex;
	complex.Re = 1;
	ComplexUser.Dump();

	//still ok
	var ComplexUser2 = new ComplexUser();
	ComplexUser2.complex.Re = 1;
	ComplexUser2.Dump();
}

class ComplexUser
{
	private Complex _complex = new Complex();
	public Complex complex { get { return _complex; } }
}

class Complex
{
	private double re;
	private double im;

	public double Re
	{
		set { this.re = value; }
		get { return this.re; }
	}
	public double Im
	{
		set { this.im = value; }
		get { return this.im; }
	}

	public double Abs
	{
		get { return Math.Sqrt(re * re + im * im); }
	}
}
```

```c#
void Main()
{

	//ok
	var ComplexUser = new ComplexUser();
	var complex = ComplexUser.complex;
	complex.Re = 1;
	ComplexUser.Dump();

	// error
  // CS1612 Cannot modify the return value of 'UserQuery.ComplexUser.complex' because it is not a variable
	var ComplexUser2 = new ComplexUser();
	ComplexUser2.complex.Re = 1;
	ComplexUser2.Dump();
}

struct ComplexUser
{
	private Complex _complex = new Complex();
	public Complex complex { get { return _complex; } }
}

class Complex
{
	private double re;
	private double im;

	public double Re
	{
		set { this.re = value; }
		get { return this.re; }
	}
	public double Im
	{
		set { this.im = value; }
		get { return this.im; }
	}

	public double Abs
	{
		get { return Math.Sqrt(re * re + im * im); }
	}
}
```