如何检测函数是否被称为构造函数？

public class MyClass {
    public MyClass() {
        if (this instanceof MyClass) {
            System.out.println("This is a constructor.");
        }
    }
}

public class MyClass {
    public MyClass() {
        if (this is MyClass) {
            Console.WriteLine("This is a constructor.");
        }
    }
}

class MyClass:
    def __init__(self):
        if self.__class__.__name__ == 'MyClass':
            print("This is a constructor.")

class MyClass {
    constructor() {
        if (this instanceof MyClass) {
            console.log("This is a constructor.");
        }
    }
}