How to see documentation of inbuilt functions on Jupyter Notebook?

Question

I recently researched about finding documentation of any inbuilt python library's function within a cell of Jupyter Notebook. Any suggestion how I can access the documentation?. I know keyboard shortcut which is shift + tab, and with 4 times shift + tab, whole documentation with example pops up. I am just wondering the usual way, apart from shortcut.

Solution

The documentation comes from the docstring in the Python code.

You can see it by calling help, and the __doc__ attribute returns the string.

Taking the built-in filter as example:

# Displays the documentation for filter function
help(filter)
# Obtains the string of the documentation.
docstring = filter.__doc__