def power_n( data, power=2.0, verbose=False ):
    """Returns the voxel-wise power of either a data array or a NIfTI-1 image object.
    
    To get the nth root, use 1/power.
    nth root of either a data array or a NIfTI image object.
    
    E.g. power_n(nii, 1./3) returns a NIfTI image whose voxel values are cube rooted.
    """
    
    if verbose:
        if power < 1.0:
            print("  Getting root-{0} of image data ...".format(power))
        else:
            print("  Getting image data^{0} ...".format(power))

    return data ** power
    # End of power_n() definition