brainfuck implementation in python with debugging

bf.py

#!/usr/bin/env python3
DEBUG = True

def debug(ip, program, dp, tape, stack):
	global DEBUG
	if DEBUG:
		print(program)
		print('{}{}{}'.format(' ' * ip, '^', ip))
		for n, d in enumerate(tape):
			if n == dp:
				print('<{}>'.format(d), '', end='')
			else:
				print(d, '', end='')
		print()
		if input('q to quit debugging:') == 'q':
			DEBUG = False

def main(program):
	stack = list()
	ip = 0
	dp = 0
	tape = [0, ]
	while ip < len(program):
		debug(ip, program, dp, tape, stack)
		c = program[ip]
		if c == '>':
			dp += 1
			if dp >= len(tape):
				tape.append(0)
		elif c == '<':
			if dp:
				dp -= 1
				if not tape[-1]:
					del tape[-1]
			else:
				print('warning: move pointer before tape')
		elif c == '+':
			tape[dp] += 1
		elif c == '-':
			tape[dp] -= 1
		elif c == '.':
			print(chr(tape[dp]), end='')
		elif c == ',':
			pass
		elif c == '[':
			if tape[dp]:
				stack.append(ip)
			else:
				cnt = 1
				while cnt:
					ip += 1
					if program[ip] == '[':
						cnt += 1
					elif program[ip] == ']':
						cnt -= 1
		elif c == ']':
			if stack:
				if tape[dp]:
					ip = stack[-1]
				else:
					stack.pop()
			else:
				print('warning: to many ]')
		ip += 1
	return tape[dp]

main('++++++++++[>+++++++>++++++++++>+++>+<<<<-]>++.>+.+++++++..+++.>++.<<+++++++++++++++.>.+++.------.--------.>+.>.+++.')