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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 boundaries(nside, pix, step=1, nest=False):
 """Drop-in replacement for healpy `~healpy.boundaries`."""

    pix = np.asarray(pix)
    if pix.ndim > 1:
        # For consistency with healpy we only support scalars or 1D arrays
        raise ValueError("Array has to be one dimensional")
    lon, lat = boundaries_lonlat(pix, step, nside, order='nested' if nest else 'ring')
    rep_sph = UnitSphericalRepresentation(lon, lat)
    rep_car = rep_sph.to_cartesian().xyz.value.swapaxes(0, 1)
    if rep_car.shape[0] == 1:
        return rep_car[0]
    else:
        return rep_car