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

Code words in text are shown as follows: "We can include other contexts through the use of the include directive."

A block of code is set as follows:

from Tkinter import *
class MyFirstGUI():
  def __init__(self):
    self.root = Tk()
    self.root.mainloop()
if __name__ == '__main__':
app = MyFirstGUI()

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

from Tkinter import *
class MyFirstGUI():
  def __init__(self):
    self.root = Tk()
    self.root.mainloop()
if __name__ == '__main__':
app = MyFirstGUI()

Any input on Python interactive shell is written as follows:

>>> import Tkinter 
>>> help(Tkinter.Label)

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "When a user specifies a new number and clicks on the Update Record button it calls a method."