* Lists
*** Outline
***** Lists
***** Tuples
***** Arsenal Required
*** Script
	Welcome friends. 

	In this tutorial we shall look at Data structures supported by
	Python.	We shall look at Lists and Tuples. We have already seen
	lists in some of previous sessions, here we shall cover more 
	details about them.

	The list type is a container that holds a number of other 
	objects, in a given order. The list type implements the sequence
	protocol, and also allows you to add and remove objects from 
	the sequence. 
	
	First lets start the interpreter by typing ipython in terminal.
	We create our first list by typing 
	num = [1, 2, 3, 4]
	Items enclosed in square brackets separated by comma 
	constitutes a list.
	One neat feature of Python list is we can store data belonging
	to multiple kind of data structures. We can have a list with 
	something:
	var = [1, 1.2, 'string']
	print var
	and with this list we can perform most of list operations.
	Python lists are very versatile, that is we can change it as we 
	wish. It supports features like removal, addition. 

	Similar to strings, we can concatenate two lists using '+' 
	operator
	so num + var will return a new list with 'var' added in end of
	'num'
	We have already covered append functionality.
	To add single object at end of list 'append' function is used
	num
	num.append(-5)
	num
	append takes only one argument. And append behaves different 
	from + operator. While + will return new list with two lists 
	added if we try similar with append function like:
	num.append([9, 10, 11])
	num
	It changes original list and add the argument as one element
	and not separate elements.
	To extend list with new list elements we use 'extend' function
	num = [1, 4, -6]
	num.extend([2, 8, 0])
	num
	As we can notice extend and append behaves differently.
	To reverse a list 'reverse' function is available. 
	num
	This is current content of list
	num.reverse()
	Now after using reverse function, lets check the value of 'num'
	num
	To remove a particular element from list Python provides remove
	num.reverse(8)
	if argument is present more than once, then first occurrence is
	removed from list.

	Slicing and Striding concepts which we covered for Arrays work
	with lists also. Lets revisit the concept with some examples
	a = [1, 2, 3, 4, 5]
	a[1:3] returns a list with second and third element of a
	One important feature of list indexing is negative values. In
	Lists -1 indicates last element of a list
	a[-1]
	similarly -2 will be second last and so forth. Now these 
	negative indexes can also be used with slicing. If we try
	a[1:-1]
	we get list which excludes first and last element of a.
	and if we miss start/end index value default are taken
	a[:3] will return list from start till fourth element of a.
	If we give step size we can do striding also
	a[1:-1:2]
	This gives second, fourth and so on items of a till we reach 
	last item of list.
	a[::2] will skip all the even placed elements of a
	With step sizes, if we give negative values we get some 
	interesting results. Lets try
	a[::-1]
	It returns reversed 'a'
	We can check for containership also with lists
	num
	4 in a
	True
	
	Python provides support to special immutable lists known as
	'tuple'	To create a tuple instead of square brackets'[' we have
	to use normal brackets '('
	t = (1, 2, 3, 4, 5, 6, 7, 8)
	its elements can also be accessed using indexes
	t[0] + t[3] + t[-1]
	but operation like
	t[4] = 7 are not allowed
	These features of tuples have their advantages. To see where 
	are they used we first create two variables
	a, b = 1, 6
	print a, b
	Now lets swap values their values. Normal approach would be 
	to create a temporary to hold the value but because of tuples
	we can do something cool like
	b, a = a, b
	print a, b
	and values are swapped. And this swapping works for all types
	of variables.
	
	With this we come to the end of this tutorial on Lists and 
	tuples. In this tutorial we have learnt some more operations 
	on lists and tuples. In next session we will cover more on 
	Python supported data structures. Thank you!

*** Notes