In this kata, you will make a function that converts between `camelCase`, `snake_case`, and `kebab-case`.

You must write a function that changes to a given case. It must be able to handle all three case types:

```python
py> change_case("snakeCase", "snake")
"snake_case"
py> change_case("some-lisp-name", "camel")
"someLispName"
py> change_case("map_to_all", "kebab")
"map-to-all"
py> change_case("doHTMLRequest", "kebab")
"do-h-t-m-l-request"
py> change_case("invalid-inPut_bad", "kebab")
None
py> change_case("valid-input", "huh???")
None
py> change_case("", "camel")
""
```

Your function must deal with invalid input as shown, though it will only be passed strings. Furthermore, all valid identifiers will be lowercase except when necessary, in other words on word boundaries in `camelCase`.

_**(Any translations would be greatly appreciated!)**_

```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 = "def discover_case(identifier):\n    if identifier is None:\n        return None\n    elif identifier == '':\n        return ''\n    elif is_camel(identifier):\n        return 'camel'\n    elif is_snake(identifier):\n        return 'snake'\n    elif is_kebab(identifier):\n        return 'kebab'\n    return None\n\ndef is_camel(identifier):\n    found_uppercase = False\n    \n    for index, ch in enumerate(identifier):\n        if not ch.isalnum():\n            return False\n        elif index != 0 and ch.isalpha() and ch.isupper():\n            found_uppercase = True\n            \n    return found_uppercase\n\ndef is_snake(identifier):\n    for ch in identifier:\n        if ch.isupper():\n            return False\n            \n    return '_' in identifier and '-' not in identifier\n\ndef is_kebab(identifier):\n    for ch in identifier:\n        if ch.isupper():\n            return False\n            \n    return '-' in identifier and '_' not in identifier\n\ndef split_words(identifier, case):\n    if case == 'camel':\n        words = []\n        word = ''\n        \n        for ch in identifier:\n            if ch.isupper():\n                words.append(word.lower())\n                word = ch\n            else:\n                word += ch\n                \n        words.append(word.lower())\n        return words\n    elif case == 'snake':\n        return identifier.split('_')\n    elif case == 'kebab':\n        return identifier.split('-')\n    else:\n        return None\n\ndef to_camel(words):\n    result = ''\n    for index, word in enumerate(words):\n        if index == 0:\n            result += word\n        else:\n            result += word.capitalize()\n    return result\n\ndef to_snake(words):\n    return '_'.join(words)\n\ndef to_kebab(words):\n    return '-'.join(words)\n\ndef change_case(identifier, targetCase):\n    case = discover_case(identifier)\n    if not case:\n        return case\n        \n    words = split_words(identifier, case)\n    if not words:\n        return None\n    \n    if targetCase == 'camel':\n        return to_camel(words)\n    elif targetCase == 'snake':\n        return to_snake(words)\n    elif targetCase == 'kebab':\n        return to_kebab(words)\n    else:\n        return None\n"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'change_case'
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: 6315