Почему не работает функция help в Python?

Invoke the built-in help system. (This function is intended for interactive use.) If no argument is given, the interactive help system starts on the interpreter console. If the argument is a string, then the string is looked up as the name of a module, function, class, method, keyword, or documentation topic, and a help page is printed on the console. If the argument is any other kind of object, a help page on the object is generated.

>>> help('spam')
No Python documentation found for 'spam'.
Use help() to get the interactive help utility.
Use help(str) for help on the str class.