Nullable

Nullable is the acknowledgment that not everything is defined —
that the presence of a property does not guarantee the presence of its meaning.

public class Human : BaseEntity
{
    public string? Mission { get; set; }
    public Action? OnAwakening;
}

You may have:
  string? Identity
  DateTime? AwakeningDate
  Action? OnLove

But if the value is unset — it is not an error.
It is a state of uncertainty: potential that may, but need not, be realized.

Nullability is the space of freedom and risk.
Because attempting to use null without a check
may result in NullReferenceException.

The base behavior is implemented as:

if (Mission != null)
    Console.WriteLine($"I live for: {Mission}");
else
    Console.WriteLine("Still searching...");

In legacy programming, everything was assumed required.
In the modern approach, we consciously allow undefined states — gaps, waiting to be filled.

? is the symbol of an open question.
A sign that not everything is known, not everything is filled — but the type already exists: meaning, potential is present.

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