old_contents: from reg import *
  
  INSTR = 'INSTR'
  
  def goto(label):
  	assign(INSTR, label)
  
  def goto_continue():
  	goto(fetch(CONT))
  
  def goto_eval():
  	goto('EVAL_EXP')
  
  def execute():
  	labels = {
  		'EVAL_EXP': evalExp
  	}
  
  	label = fetch(INSTR)
  
  	try:
  		label()
  	except:
  		raise Exception('Unknown label: {}'.format(label))
new_contents: from reg import *
  
  INSTR = 'INSTR'
  
  
  def goto(label):
  	assign(INSTR, label)
  
  def goto_continue():
  	goto(fetch(CONT))
  
  def goto_eval():
  	goto(EVAL_EXP)
  
  def execute():
  	labels = {
  		EVAL_EXP: evalExp
  	}
  
  	label = fetch(INSTR)
  
  	try:
  		label()
  	except:
  		raise Exception('Unknown label: {}'.format(label))
  
  # labels (separate file?)
  
  EVAL_EXP = 'EVAL_EXP'
  
subject: Add list of labels to instr