During copy/pasting code I often get null bytes in Python code. Python itself reports general error against module and doesn't specify location of null byte. IDE of my choice like PyCharm, doesn't have check for this and doesn't see null bytes in code.

So, what is the general way to find null bytes in Python code?

λ cat main.py
import helloworld
λ cat helloworld.py
print('Hello world! ')
λ python main.py
Traceback (most recent call last):File "main.py", line 1, in <module>import helloworld
ValueError: source code string cannot contain null bytesλ python helloworld.pyFile "helloworld.py", line 1print('Hello world!^
SyntaxError: EOL while scanning string literalλ cat -A helloworld.py
print('Hello world!^@')

The issue is likely caused by copy/paste, since it's hard to type such a character on the keyboard.

So, what is the general way to find null bytes in Python code?

IMHO there's no need to check for NUL chcracters in your source code every time. I'm working with source code for >10 years now, and I've never had such a copy/paste issue, even I use copy/paste for many prototypes and MCVEs.

So, the trigger to check the source code is exactly an error message such as the one from Python.

Which tool to use? A hex editor, since it will display the NUL character. For Windows, my choice is the freeware HxD.

On Linux, the command grep -Pa '\x00' helloworld.py should be fine.