def __iter__(self):
        """
        Iterate over pairs.

        Yields
        ------
        int
            Position of the first window in the dataset.
        int
            Position of the second window in the dataset.
        float
            0 for a negative pair, 1 for a positive pair.
        """
        for i in range(self.n_examples):
            if hasattr(self, "examples"):
                yield self.examples[i]
            else:
                yield self._sample_pair()

        Iterate over pairs.

        Yields
        ------
        int
            Position of the first window in the dataset.
        int
            Position of the second window in the dataset.
        float
            0 for a negative pair, 1 for a positive pair.
        
braindecode/samplers/ssl.py