>>> import inspect, struct
>>> help(struct.pack)
Help on built-in function pack in module _struct:
pack(...)
 pack(format, v1, v2, ...) -> bytes
 Return a bytes object containing the values v1, v2, ... packed according
 to the format string. See help(struct) for more on format strings.
>>> inspect.signature(struct.pack)
Traceback (most recent call last):
 File "<python-input-6>", line 1, in <module>
 inspect.signature(struct.pack)
 ~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
 File "/usr/local/lib/python3.15/inspect.py", line 3346, in signature
 return Signature.from_callable(obj, follow_wrapped=follow_wrapped,
 ~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 globals=globals, locals=locals, eval_str=eval_str,
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 annotation_format=annotation_format)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 File "/usr/local/lib/python3.15/inspect.py", line 3061, in from_callable
 return _signature_from_callable(obj, sigcls=cls,
 follow_wrapper_chains=follow_wrapped,
 globals=globals, locals=locals, eval_str=eval_str,
 annotation_format=annotation_format)
 File "/usr/local/lib/python3.15/inspect.py", line 2542, in _signature_from_callable
 return _signature_from_builtin(sigcls, obj,
 skip_bound_arg=skip_bound_arg)
 File "/usr/local/lib/python3.15/inspect.py", line 2326, in _signature_from_builtin
 raise ValueError("no signature found for builtin {!r}".format(func))
ValueError: no signature found for builtin <built-in function pack>