def _move_delta_lbound(d, bytes):
	"""Move the delta by the given amount of bytes, reducing its size so that its
	right bound stays static
	:param bytes: amount of bytes to move, must be smaller than delta size
	:return: d"""
	if bytes == 0:
		return
		
	d.to += bytes
	d.so += bytes
	d.ts -= bytes
	if d.data is not None:
		d.data = d.data[bytes:]
	# END handle data
	
	return d