Brainf*ck (a language named brainf*ck but not BF) interpreter

# See esolang wiki: https://esolangs.org/wiki/Brainf_ck for specification
import sys

# Code:
def brainf_ck(code,stack):
    code=''.join(filter(lambda x:x in '+-,.[]<>',code))
    if code=='+':
        return 1
    if code=='-':
        return stack.pop()
    if code==',':
        c=sys.stdin.read(1)
        if c:
            return ord(c)
        else:
            return 0
    if code=='.':
        print(chr(stack[-1]),end='')
        return stack[-1]
    code = code.replace('>[', '(').replace(']<', ')')  # Make instructions 1 byte
    parts=[]
    ip=0
    while ip<len(code):
        i=code[ip]
        if i=='+':
            parts.append('+')
            ip+=1
        if i=='-':
            parts.append('-')
            ip+=1
        if i==',':
            parts.append(',')
            ip+=1
        if i=='.':
            parts.append('.')
            ip+=1
        if i=='(':
            m=1
            t='('
            while m:
                ip+=1
                if code[ip]=='(':
                    m+=1
                if code[ip]==')':
                    m-=1
                t+=code[ip]
            parts.append(t)
            ip+=1
        if i=='[':
            m=1
            t='['
            while m:
                ip+=1
                if code[ip]=='[':
                    m+=1
                if code[ip]==']':
                    m-=1
                t+=code[ip]
            parts.append(t)
            ip+=1
    if len(parts)==1:
        if code[0]=='(':
            stack.append(brainf_ck(code[1:-1].replace('(','>[').replace(')',']<'),stack))
            return stack[-1]
        else:
            while stack and stack[-1]:
                brainf_ck(code[1:-1].replace('(','>[').replace(')',']<'),stack)
            return 0
    else:
        su=0
        for i in parts:
            k=brainf_ck(i.replace('(','>[').replace(')',']<'),stack)
            su+=k
            su&=255
        return su

# Usage:
brainf_ck('<code>',[])

# You may extend Python's recursion limit if you want:
sys.setrecursionlimit(10000)