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+.. Objectives
+.. ----------
+
+.. By the end of this tutorial, you will be able to
+
+.. 1. Slice strings and get sub-strings out of them
+.. #. Reverse strings
+.. #. Replace characters in strings. 
+.. #. Convert strings to upper or lower case
+.. #. joining a list of strings
+
+.. Prerequisites
+.. -------------
+
+..   1. getting started with strings
+..   #. getting started with lists
+..   #. basic datatypes
+     
+.. Author              : Puneeth 
+   Internal Reviewer   : Amit 
+   External Reviewer   :
+   Language Reviewer   : Bhanukiran
+   Checklist OK?       : <08-11-2010, Anand, OK> [2010-10-05]
+
+Script
+------
+
+{{{ Show the slide containing title }}}
+
+Hello Friends. Welcome to this tutorial on manipulating strings. 
+
+{{{ show the slide with outline }}} 
+
+In this tutorial we shall learn to manipulate strings, specifically
+slicing and reversing them, or replacing characters, converting from
+upper to lower case and vice-versa and joining a list of strings.
+
+We have an ``ipython`` shell open, in which we are going to work,
+through out this session. 
+
+Let us consider a simple problem, and learn how to slice strings and
+get sub-strings. 
+
+Let's say the variable ``week`` has the list of the names of the days
+of the week. 
+
+::
+
+    week = ["sun", "mon", "tue", "wed", "thu", "fri", "sat"]
+
+
+Now given a string ``s``, we should be able to check if the string is a
+valid name of a day of the week or not. 
+
+::
+
+    s = saturday
+
+
+``s`` could be in any of the forms --- sat, saturday, Sat, Saturday,
+SAT, SATURDAY. For now, shall now be solving the problem only for the forms,
+sat and saturday. We shall solve it for the other forms, at the end of
+the tutorial. 
+
+{{{ show these forms in a slide }}}
+
+So, we need to check if the first three characters of the given string
+exists in the variable ``week``. 
+
+As, with any of the sequence data-types, strings can be sliced into
+sub-strings. To get the first three characters of s, we say,
+
+::
+
+    s[0:3]
+
+Note that, we are slicing the string from the index 0 to index 3, 3
+not included. 
+
+As we already know, the last element of the string can be accessed
+using ``s[-1]``.  
+
+Following is an exercise that you must do. 
+
+%%1%% Obtain the sub-string excluding the first and last characters
+from the string s. 
+
+Please, pause the video here. Do the exercise(s) and then continue. 
+
+::
+
+    s[1:-1]
+
+gives the substring of s, without the first and the last
+characters of s. 
+
+::
+
+    s = saturday
+    s[:3]
+
+Now, we just check if that substring is present in the variable
+``week``. 
+
+::
+
+    s[:3] in week          
+
+Let us now consider the problem of finding out if a given string is
+palindromic or not. First of all, a palindromic string is a string
+that remains same even when it has been reversed.
+
+Let the string given be ``malayalam``.
+
+::
+
+    s = "malayalam"
+
+Now, we need to compare this string with it's reverse. 
+
+Again, we will use a technique common to all sequence data-types,
+[::-1]
+
+So, we obtain the reverse of s, by simply saying, 
+
+::
+
+    s[::-1]
+
+Now, to check if the string is ``s`` is palindromic, we say
+::
+
+    s == s[::-1]
+
+As, expected, we get ``True``. 
+
+Now, if the string we are given is ``Malayalam`` instead of
+``malayalam``, the above comparison would return a False. So, we will
+have to convert the string to all lower case or all upper case, before
+comparing. Python provides methods, ``s.lower`` and ``s.upper`` to
+achieve this. 
+
+Let's try it out. 
+::
+
+   s = "Malayalam"
+
+   s.upper()
+
+   s
+
+As you can see, s has not changed. It is because, ``upper`` returns a
+new string. It doesn't change the original string. 
+
+::
+
+   s.lower()
+
+   s.lower() == s.lower()[::-1]
+   
+Following is an exercise that you must do. 
+
+%%2%% Check if ``s`` is a valid name of a day of the week. Change the
+solution to this problem, to include forms like, SAT, SATURDAY,
+Saturday and Sat.
+
+Please, pause the video here. Do the exercise and then continue. 
+
+::
+
+    s in week
+
+    s.lower()[:3] in week
+
+
+So, as you can see, now we can check for presence of ``s`` in
+``week``, in whichever format it is present -- capitalized, or all
+caps, full name or short form.
+
+We just convert any input string to lower case and then check if it is
+present in the list ``week``. 
+
+Now, let us consider another problem. We often encounter e-mail id's
+which have @ and periods replaced with text, something like
+info[at]fossee[dot]in. We now wish to get back proper e-mail
+addresses.  
+
+Let's say the variable email has the email address. 
+::
+
+   email = "info[at]fossee[dot]in"
+
+Now, we first replace the ``[at]`` with the ``@``, using the replace
+method of strings. 
+::
+
+   email = email.replace("[at]", "@")
+   print email
+
+Following is an exercise that you must do. 
+
+%%3%% Replace the ``[dot]`` with ``.`` in ``email``
+
+Please, pause the video here. Do the exercise and then continue. 
+
+::
+
+   email = email.replace("[dot]", ".")        
+   print email
+
+Now, let's look at another interesting problem where we have a list of
+e-mail addresses and we wish to obtain one long string of e-mail
+addresses separated by commas or semi-colons. 
+
+::
+
+  email_list = ["info@fossee.in", "enquiries@fossee.in",  "help@fossee.in"]
+
+
+Now, if we wish to obtain one long string, separating each of the
+email id by a comma, we use the join operator on ``,``. 
+
+::
+
+  email_str = ", ".join(email_list)
+  print email_str
+
+Notice that the email ids are joined by a comma followed by a space. 
+
+Following is an exercise that you must do. 
+
+%%3%% From the email_str that we generated, change the separator to be
+a semicolon instead of a comma. 
+
+Please, pause the video here. Do the exercise and then continue. 
+
+::
+
+  email_str = email_str.replace(",", ";")
+
+That brings us to the end of the tutorial. 
+
+{{{ show summary slide }}}
+
+In this tutorial, we have learnt how to get substrings, reverse
+strings and a few useful methods, namely upper, lower, replace and
+join. 
+
+{{{ Show the "sponsored by FOSSEE" slide }}}
+
+This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India
+
+Hope you have enjoyed and found it useful.
+Thank you!
+