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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 level_ipix_to_uniq(level, ipix):
 """ Convert a level and HEALPix index into a uniq number representing the cell. This function is the inverse of `uniq_to_level_ipix`. Parameters level : int The level of the HEALPix cell ipix : int The index of the HEALPix cell Returns ------- uniq : int The uniq number representing the HEALPix cell. """

    level = np.asarray(level, dtype=np.int64)
    ipix = np.asarray(ipix, dtype=np.int64)

    _validate_level(level)
    _validate_npix(level, ipix)

    return ipix + (1 << 2*(level + 1))