Python Why .upper change type of string

I have a problem with my hangman project. When matching user input (lower case) with the word to guess (upper case), I’m using .upper which is causing an error.

if user_input.upper in self.word_to_guess:
                indexes = self.find_indexes(user_input)
                self.update_progress(user_input, indexes)

                # If there is no letter to find in the word

                if self.game_progress.count('_') == 0:
                    print('\n¡Yay! You win!')
                    print('The word is: {0}'.format(self.word_to_guess))
                    quit()

and I test that .upper change <class ‘str’> to <class ‘builtin_function_or_method’>

M = 'me'
print(M)
print(type(M))
print('')

M =(M.upper)
print(str(M))
print(type(M))
print('')

result

me
<class 'str'>

<built-in method upper of str object at 0x00007FFA191B1200>
<class 'builtin_function_or_method'>

I can convert those words to lowercase. However, I need to know how to use .upper() to change only ‘me’ to ‘ME’, without changing it into a class.’builtin_function_or_method’

>Solution :

You are not calling the method, but referencing it instead.

By doing M.upper you are making M equal to the upper method instead of actually running it.

M.upper() will run the method and return the result