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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 _read_atlas_zonefile( zonefile_path, zonefile_hash ):
 """ Read and verify an atlas zone file """


    with open(zonefile_path, "rb") as f:
        data = f.read()

    # sanity check 
    if zonefile_hash is not None:
        if not verify_zonefile( data, zonefile_hash ):
            log.debug("Corrupt zonefile '%s'" % zonefile_hash)
            return None

    return data