Define two functions: `hex_to_bin` and `bin_to_hex` (or `hexToBin` and `binToHex`)


# hex_to_bin

Takes a hexadecimal string as an argument .

**Note:** This string can contain upper or lower case characters and start with any amount of zeros.

Returns the binary representation (without leading zeros) of the numerical value of the hexadecimal string.

Examples:

```
"00F"    -->  "1111"
"5"      -->  "101"
"00000"  -->  "0"
"04D2"   -->  "10011010010"
```

# bin_to_hex

Takes a binary string (with or without leading zeros) as an argument .

Returns the hexadecimal representation of the numerical value of the binary string.

**Note:** Any non-numerical characters should be lower case


Examples:

```
"1111"         -->  "f"
"000101"       -->  "5"
"10011010010"  -->  "4d2"
```

**Note:** You can assume all arguments are valid so there is no need for error checking.

Oh, and I've disabled a few things.


Any feedback would be much 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 = "h = '0123456789abcdef'\n\ndef bin_to_hex(binary_string):\n    n = 0\n    for x in binary_string:\n        n = n * 2 + (x == '1')\n    result = []\n    while n:\n        n, r = divmod(n, 16)\n        result.append(h[r])\n    return ''.join(result[::-1]) or '0'\n\ndef hex_to_bin(hex_string):\n    n = 0\n    for x in hex_string.lower():\n        n = n * 16 + h.find(x)\n    result = []\n    while n:\n        n, r = divmod(n, 2)\n        result.append(h[r])\n    return ''.join(result[::-1]) or '0'"
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'bin_to_hex'
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: 5534