Conventions

In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: " We need the random library for the randint() function, which returns a random integer in the provided range."

A block of code is set as follows:

def fractal_tree(b_len,t):
    if b_len > 5:
        temp=random.randint(1, b_len)
        temp_angle = random.randint(1, 25)
        t.forward(temp)
        t.right(temp_angle)
        fractal_tree(b_len-10,t)
        t.left(2 * temp_angle)
        fractal_tree(b_len-10,t)
        t.right(temp_angle)
        t.backward(temp)

Any command-line input or output is written as follows:

pi@raspberrypi ~ $ mkdir book
pi@raspberrypi ~ $ cd book
pi@raspberrypi ~/book $ pwd
/home/pi/book
pi@raspberrypi ~/book $ 

New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: " Check out the Product page of Raspberry Pi at