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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 purview(repertoire):
 """The purview of the repertoire. Args: repertoire (np.ndarray):
 A repertoire Returns: tuple[int]: The purview that the repertoire was computed over. """

    if repertoire is None:
        return None

    return tuple(i for i, dim in enumerate(repertoire.shape) if dim == 2)