https://docs.python.org/3.5/tutorial/stdlib.html I might be wrong (English is not my mother-tongue) but in the following sentence in section 10.1 seems to be an error. The built-in dir() <https://docs.python.org/3.5/library/functions.html#dir>

and help() <https://docs.python.org/3.5/library/functions.html#help> functions are useful as interactive aids for working with large modules like os <https://docs.python.org/3.5/library/os.html#module-os>:

Shouldn't the plural of aide be aides? Greetings, Mat