Reading manual pages

When the libraries are imported in IPython, we can open manual pages for library functions with the help command. It is not necessary to know the name of a function. We can type a few characters and then let the tab completion do its work. Let's, for instance, browse the available information for the arange() function.

We can browse the available information in either of the following two ways:

• Calling the help function: Type in help( followed by a few characters of the function and press the Tab key. A list of functions will appear. Select the function from the list using the arrow keys and press the Enter key. Close the help function call with )  and press the Enter key.
  
• Querying with a question mark: Another option is to append a question mark to the function name. You will then, of course, need to know the function name, but you don't have to type help, for example:

  In [3]: numpy.arange?
  

  Tab completion is dependent on readline, so you need to make sure that it is installed. It can be installed with pip by typing the following command:

  $ pip3 install readline
  

  The question mark gives you information from docstrings.