Incorporated feedback from lodin/adambard/others

Changes:

- Added a few lines on using "is" to compare object identity.
- Removed example about lists containing arbitrary values.
- Removed example about assigning lambdas to variables.
- Removed example about dictionary comprehensions.
- Removed the additional explanation about 'self'
- Added a clarification on modules.

python.html.markdown

@@ -98,6 +98,10 @@ None #=> None
 "etc" is None #=> False
 None is None  #=> True
 
+# The 'is' operator tests for object identity. This isn't
+# very useful when dealing with primitive values, but is
+# very useful when dealing with objects.
+
 # None, 0, and empty strings/lists all evaluate to False.
 # All other values are True
 0 == False  #=> True
@@ -169,9 +173,6 @@ li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6]
 # Examine the length with len
 len(li) #=> 6
 
-# Note: lists can contain arbitrary values
-li2 = [1, "Hello", [[], "Hi", 5,]]
-
 # Tuples are like lists but are immutable.
 tup = (1, 2, 3)
 tup[0] #=> 1
@@ -375,8 +376,6 @@ add_10(3) #=> 13
 
 # There are also anonymous functions
 (lambda x: x > 2)(3) #=> True
-rectangle_area = lambda a, b: a * b
-print rectangle_area(3, 4) #=> 12
 
 # There are built-in higher order functions
 map(add_10, [1,2,3]) #=> [11, 12, 13]
@@ -386,9 +385,6 @@ filter(lambda x: x > 5, [3, 4, 5, 6, 7]) #=> [6, 7]
 [add_10(i) for i in [1, 2, 3]]  #=> [11, 12, 13]
 [x for x in [3, 4, 5, 6, 7] if x > 5] #=> [6, 7]
 
-# You can also use dictionary comprehensions
-{i: add_10(i) for i in [1, 2, 3]} #=> {1: 11, 2: 12, 3: 13}
-
 ####################################################
 ## 5. Classes
 ####################################################
@@ -404,8 +400,7 @@ class Human(object):
         # Assign the argument to the instance's name attribute
         self.name = name
 
-    # An instance method. All methods take self as the first argument,
+    # An instance method. All methods take self as the first argument
-    # which refers to the instance of this class
     def say(self, msg):
        return "%s: %s" % (self.name, msg)
 
@@ -462,7 +457,8 @@ import math as m
 math.sqrt(16) == m.sqrt(16) #=> True
 
 # Python modules are just ordinary python files. You
-# can write your own, and import them.
+# can write your own, and import them. The name of the 
+# module is the same as the name of the file.
 
 
 ```