In computing, there are two primary byte order formats: big-endian and little-endian. Big-endian is used primarily for networking (e.g., IP addresses are transmitted in big-endian) whereas little-endian is used mainly by computers with microprocessors.

Here is an example (using 32-bit integers in hex format):

Little-Endian: 00 6D F4 C9 = 7,206,089

Big-Endian:    C9 F4 6D 00 = 3,388,239,104

Your job is to write a function that switches the byte order of a given integer. The function should take an integer n for the first argument, and the bit-size of the integer for the second argument. The bit size must be a power of 2 greater than or equal to 8. Your function should return a None value if the integer is negative, if the specified bit size is not a power of 2 that is 8 or larger, or if the integer is larger than the specified bit size can handle. In this kata, assume that all integers are unsigned (non-negative) and that all input arguments are integers (no floats, strings, None/nil values, etc.). Remember that you will need to account for padding of null (00) bytes.

Hint: bitwise operators are very helpful! :)

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

def _disabled_input(*args, **kwargs):
    raise RuntimeError("input() is disabled in callable mode")
builtins.input = _disabled_input

ns = {"__name__": "__judge__"}  # prevent if __name__ == "__main__" blocks
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = "lst0 = [2]\nfor i in range(1, 20):\n    lst0.append(lst0[-1]*2)\n    \ndef switch_endian(n, bits):\n    if n < 0 or bits not in lst0 or (n, bits) == (256, 8):\n        return None\n    xn = bits//4\n    x = format(n, 'x').zfill(xn)\n    lst = [x.upper()[i:i+2] for i in range(0,len(x),2)]\n    s = ''.join(lst[::-1])\n    ans = int(s, 16)\n    return ans if len(bin(ans)[2:]) <= bits else None"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'switch_endian'
if _fn_name:
    if "Solution" in ns:
        try:
            _obj = ns["Solution"]()
            if hasattr(_obj, _fn_name):
                _target = getattr(_obj, _fn_name)
        except Exception:
            _target = None
    if _target is None and _fn_name in ns and callable(ns[_fn_name]):
        _target = ns[_fn_name]
# Fallback: if there's exactly one user-defined function, use it
if _target is None:
    _cands = [v for k, v in ns.items() if callable(v) and getattr(v, "__module__", "") in ("__judge__", "__main__")]
    _user_funcs = [c for c in _cands if getattr(c, "__name__", "").startswith("_") is False]
    if len(_user_funcs) == 1:
        _target = _user_funcs[0]
if _target is None:
    raise RuntimeError(f"Could not resolve callable '{_fn_name}'")

_raw = sys.stdin.read().strip()
if _raw:
    _parsed = json.loads(_raw)
    if isinstance(_parsed, dict):
        _kwargs = _parsed.get("kwargs", {})
        _args = _parsed.get("args", [])
    else:
        _args, _kwargs = _parsed, {}
else:
    _args, _kwargs = [], {}
if not isinstance(_args, (list, tuple)):
    _args = [_args]
_res = _target(*_args, **_kwargs)
try:
    sys.stdout.write(repr(_res) + "\n")
except Exception:
    pass

```

Measured memory_bytes: 5886