print(doc) in Python 3 script

I can't figure out what does the print(__doc__) do at the beginning of a script, like in this Scikit example.

I have been looking for Python docstrings in google, and it seems __doc__ is useful to provide some documentation in, say, functions. But I can't see what does __doc__ do in the middle of a script.

it seems __doc__ is useful to provide some documentation in, say, functions

This is true. In addition to functions, documentation can also be provided in modules. So, if you have a file named mymodule.py like this:

    """This is the module docstring."""

    def f(x):
        """This is the function docstring."""
        return 2 * x

You can access its docstrings like this:

    >>> import mymodule
    >>> mymodule.__doc__
    'This is the module docstring.'
    >>> mymodule.f.__doc__
    'This is the function docstring.'

Now, back to your question: what does print(__doc__) do? Simply put: it prints the module docstring. If no docstring has been specified, __doc__ defaults to None.

From: stackoverflow.com/q/33066383