new_contents: def postfix(s):
  	op_stack = []
  	res = []
  	for i in s:
  		if i == ')':
  			current = op_stack.pop()
  			while current != '(':
  				res.append(current)
  				current = op_stack.pop()
  		elif i == '(':
  			op_stack.append(i)
  		elif i == '+':
  			print(op_stack)
  			while op_stack and op_stack[-1] == '*':
  				res.append(op_stack.pop())
  			op_stack.append(i)
  		elif i == '*':
  			op_stack.append(i)
  		else:
  			res.append(i)
  	op_stack.reverse()
  	res += op_stack
  	return res
  	
  print(postfix("((A+B)*C)*(D+F)"))
  
subject: Create postfix.py