def build_array_encoding(length: int, element_type_encoding: bytes) -> bytes:
	"""Build an array type encoding from a length and an element type encoding.
	
	.. note::
	
		This function currently doesn't perform any checking on ``element_type_encoding``,
		but such checks may be added in the future.
		``element_type_encoding`` should always be a valid type encoding string.
	"""
	
	if length < 0:
		raise ValueError(f"Array length cannot be negative: {length}")
	
	length_string = str(length).encode("ascii")
	return b"[" + length_string + element_type_encoding + b"]"