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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 nside_to_level(nside):
 """ Find the HEALPix level for a given nside. This is given by ``level = log2(nside)``. This function is the inverse of `level_to_nside`. Parameters nside : int The number of pixels on the side of one of the 12 'top-level' HEALPix tiles. Must be a power of two. Returns ------- level : int The level of the HEALPix cells """

    nside = np.asarray(nside, dtype=np.int64)

    _validate_nside(nside)
    return np.log2(nside).astype(np.int64)