The rgb function is incomplete. Complete it so that passing in RGB decimal values will result in a hexadecimal representation being returned. Valid decimal values for RGB are 0 - 255. Any values that fall out of that range must be rounded to the closest valid value.

Note: Your answer should always be 6 characters long, the shorthand with 3 will not work here.

The following are examples of  expected output values:
```python
rgb(255, 255, 255) # returns FFFFFF
rgb(255, 255, 300) # returns FFFFFF
rgb(0,0,0) # returns 000000
rgb(148, 0, 211) # returns 9400D3
```
```if:nasm

char \*rgb(int r, int g, int b, char \*outp)

```

```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 rgb(r, g, b):\n    """\n    Return hex string representation of ``r,g,b`` values. A saturation \\\nwill be applied to the input values to ensure they are betweem 0 \\\nand 255.\n    \n    :param r: Red channel\n    :type r: int \n    \n    :param g: Green channel\n    :type g: int \n    \n    :param b: Blue channel\n    :type b: int \n    \n    :return: Hex representation.\n    :rtype: str\n    \n    >>> rgb(123,45,67)\n    \'7B2D43\'\n    >>> rgb(-20,123,456)\n    \'007BFF\'\n    >>> rgb(\'no int\',123,123)\n    Traceback (most recent call last):\n        ...\n    TypeError: \'r\' is not of type int\n    >>> rgb(123,\'no int\',123)\n    Traceback (most recent call last):\n        ...\n    TypeError: \'g\' is not of type int\n    >>> rgb(123,123,\'no int\')\n    Traceback (most recent call last):\n        ...\n    TypeError: \'b\' is not of type int\n    """\n    \n    if not type(r).__name__ == \'int\':    # python2 does not have instanceof()\n        raise TypeError("\'r\' is not of type int")\n    if not type(g).__name__ == \'int\':    # python2 does not have instanceof()\n        raise TypeError("\'g\' is not of type int")\n    if not type(b).__name__ == \'int\':    # python2 does not have instanceof()\n        raise TypeError("\'b\' is not of type int")\n    \n    return "{r:02X}{g:02X}{b:02X}".format(\n        r=saturate(r),\n        g=saturate(g),\n        b=saturate(b),\n    )\n\n\ndef saturate(x):\n    """\n    Saturates an integer ``x`` to be ``0<=x<=255``.\n    \n    :param x: Integer to be saturated\n    :type x: int \n    \n    :return: Saturated integer\n    :rtype: int\n    \n    >>> saturate(345)\n    255\n    >>> saturate(-3)\n    0\n    >>> saturate(123)\n    123\n    >>> saturate("no int")\n    Traceback (most recent call last):\n        ...\n    TypeError: given value is not of type int\n    """\n    if not type(x).__name__ == \'int\':    # python2 does not have instanceof()\n        raise TypeError("given value is not of type int")\n    \n    x = 0 if x<0 else x\n    x = 255 if x>255 else x\n    \n    return x\n\n\ndef __starting_point():\n    import doctest\n    doctest.testmod()\n__starting_point()'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

_target = None
_fn_name = 'rgb'
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: 6049