Python's built-in string function, isupper(), returns True if a string contains only capital letters. It returns False if the string has any lowercase or non-letter characters (such as symbols or integers). Simply checking the string's condition and returning a boolean value is all that the isupper Python method accomplishes.

more details : https://docs.vultr.com/python/....standard-library/str

 

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Python str isupper() - Check Uppercase Letters | Vultr Docs