What does it mean to say "if n"?

Question

What does it mean to say if n? I don't get why if n works in an if statement. Shouldn't there be an argument such as if n == 0 or something, not just if n?

def AddMusicAtPosition(self, newMusic, n):
    if n:
        self.nextMusic.AddMusicAtPosition(newMusic, n - 1)
    else:
        newMusic.nextMusic = self.nextMusic
        self.nextMusic = newMusic

Answer 1

In Python, if n is equivalent to if bool(n).

For integers, bool(i) equals to i != 0.

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If n is an instance of a class, then

• if the class defines __bool__, then n.__bool__() is called
• if the class doesn't define __bool__ but __len__, then n.__len__() != 0 is evaluated
• if the class defines neither __bool__ nor __len__, it always evaluates to True (think like n is not None).