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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def extract_labels(self) -> np.ndarray: """Extract condition labels. Returns ------- np.ndarray The condition label of each epoch. """

        condition_idxs, epoch_idxs, _ = np.where(self)
        _, unique_epoch_idxs = np.unique(epoch_idxs, return_index=True)
        return condition_idxs[unique_epoch_idxs]