self is not defined

This error occurs when you try to use a variable or function that has not been defined in your code.

For example, if you write:

print(self.name)

and `self` has not been defined anywhere in your code, you will get a `NameError: name 'self' is not defined` error.

In Python, `self` is usually used in object-oriented programming to refer to the instance of a class. If you are not using object-oriented programming, you should not use `self`.

If you are using object-oriented programming and are getting this error, make sure that you have properly defined your class and that you are using `self` correctly within the class methods.