3.4.1 (v3.4.1:c0e311e010fc, May 18 2014, 00:54:21) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)]
Python Type "help", "copyright", "credits" or "license" for more information.

# Something familiar:
w1 = 'words'

# What is w1?  
# It is the name of a variable that refers to an object.
# The object has a type and it has contents.
# We can see the type:
type(w1)
<class 'str'>
# And get help on it:
help(str)
Help on class str in module builtins:
# (Lots of help information omitted.)

# When we want to do something with an object, we usually call a method on it.
w1.index('s')
4
w1
'words'
w1.islower()
True
w1.replace('d', 'dsmith')
'wordsmiths'
w1
'words'
# w1 is unchanged!  The replace method doesn't change the string,
# it returns a new string. In fact, method replace couldn't change w1 even if
# it wanted to because strings are immutable.

# We can also use operators to do things to with object:
'Happy' + 'New' + 'Year'
'HappyNewYear'
w1[4]
's'
w1[0]
'w'

# Let's make some more strings.
w2 = 'swords'
w3 = w2[1:]
w1
'words'
w2
'swords'
w3
'words'
w1 == w2
False
w2
'swords'
# At this point, we might say that "w1 and w3 are the same."
# Python gives us two ways to ask whether they are the same.
w1 == w3
True
w1 is w3
False
# Huh?  
# This actually makes perfect sense:
# Double equals checks whether they have the same value,
# but "is" checks whether they are the same object.
# It was sloppy to say that "w1 and w3 are the same".
# More precise would be to say that "w1 and w3 each reference
# a string object with the value 'words'."
# Or to spell it out even further, "w1 references a string
# object with the value 'words' and so does w3, but they are
# two different string objects."


# In addition to str, 
# there are many other useful types of object already defined in Python,
# including list and dictionary.
names = ['Danny', 'Catherine', 'Tom']
colleges = {'Danny': 'Vic', 'Tom':'Innis'}

# In fact, every value in Python is an object, including
# simple things like integers and booleans.
n = 3
type(n)
<class 'int'>
# Even though we normally use operators with ints ...
n + 15
18
# ... we can actually call methods on them 
# (which is a clear sign that they are objects):
n.__ceil__()
3
n.__lt__(2)
False
n.__add__(14)
17
n + 14
17