Example:

        ```py
        >>> from datasets import load_dataset
        >>> ds = load_dataset("rotten_tomatoes", split="validation")
        >>> def add_prefix(example):
        ...     example["text"] = "Review: " + example["text"]
        ...     return example
        >>> ds = ds.map(add_prefix)
        >>> ds[0:3]["text"]
        ['Review: compassionately explores the seemingly irreconcilable situation between conservative christian parents and their estranged gay and lesbian children .',
         'Review: the soundtrack alone is worth the price of admission .',
         'Review: rodriguez does a splendid job of racial profiling hollywood style--casting excellent latin actors of all ages--a trend long overdue .']