import uctypes

desc = {
    # arr is array at offset 0, of UINT8 elements, array size is 2
    "arr": (uctypes.ARRAY | 0, uctypes.UINT8 | 2),
    # arr2 is array at offset 0, size 2, of structures defined recursively
    "arr2": (uctypes.ARRAY | 0, 2, {"b": uctypes.UINT8 | 0}),
    "arr3": (uctypes.ARRAY | 2, uctypes.UINT16 | 2),
}

data = bytearray(b"01234567")

S = uctypes.struct(uctypes.addressof(data), desc, uctypes.LITTLE_ENDIAN)

print(uctypes.sizeof(S.arr))
assert uctypes.sizeof(S.arr) == 2

print(uctypes.sizeof(S.arr2))
assert uctypes.sizeof(S.arr2) == 2

print(uctypes.sizeof(S.arr3))

try:
    print(uctypes.sizeof(S.arr3[0]))
except TypeError:
    print("TypeError")