def METHOD_NAME():
    '''Generate valid test vectors'''
    while True:
        for template in templates:
            prefix = bytearray(template[0])
            payload = bytearray(os.urandom(template[1]))
            suffix = bytearray(template[2])
            rv = b58encode_chk(prefix + payload + suffix)
            assert is_valid(rv)
            metadata = {x: y for x, y in zip(metadata_keys,template[3]) if y is not None}
            hexrepr = b2a_hex(payload)
            if isinstance(hexrepr, bytes):
                hexrepr = hexrepr.decode('utf8')
            yield (rv, hexrepr, metadata)