function(a, b) Note that file is one of Python's core modules, so I suggest you change the filename of file.py to something else. Note that if you're trying to import functions from a.py to a file …

For a language-agnostic consideration of the design decision, see What is the advantage of having this/self pointer mandatory explicit?. To close debugging questions where OP omitted a …

As is, it does absolutely nothing. It is a type annotation for the main function that simply states that this function returns None. Type annotations were introduced in Python 3.5 and are specified …

def __enter__(self): return self def __exit__(self, type, value, tb): self.stream.close() Here is the complete code.

def test(): global a a = a + 10 print(a) Using the global keyword just tells the test where to look for a. With the first method, you can't modify the global variable a, because you made a copy of it …

I would like to return two values from a function in two separate variables. What would you expect it to look like on the calling end? You can't write a = select_choice(); b = select_choice() …

What does the @ symbol do in Python?What's the syntactic or practical benefit of having decorators here, instead of (for example) just calling something like app.route("/", hello) …

I am getting a NoClassDefFoundError when I run my Java application. What is typically the cause of this?

What is the main difference between class and def in python? Can a class in python interact with django UI (buttons)?

The other respondents are correct in describing the double leading and trailing underscores as a naming convention for "special" or "magic" methods. While you can call these methods directly …