def vint_mask_for_length(length):
	"""
	
	Returns the bitmask for the first byte of a variable-length integer (used for element ID and size descriptors).
	
	:arg length: the length of the variable-length integer
	:type length: int
	:returns: the bitmask for the first byte of the variable-length integer
	:rtype: int
	
	"""
	
	return 0b10000000 >> (length - 1)