diff -r cd3fdf21a6e4 Doc/faq/programming.rst
--- a/Doc/faq/programming.rst	Thu Jan 16 14:15:03 2014 -0800
+++ b/Doc/faq/programming.rst	Thu Jan 16 21:25:07 2014 -0800
@@ -208,6 +208,25 @@
 declaration for identifying side-effects.
 
 
+Why does changing one mutable object also change another mutable object?
+------------------------------------------------------------------------
+
+This happens:
+
+>>> a = [1, 2, 3]
+>>> b = a
+>>> b.append(4)
+>>> print a
+[1, 2, 3, 4]
+
+because variables are just names for things, in this case ``a`` is the list 
+we first defined and then ``b = a`` says that ``b`` is also a name for that list. 
+They are both the same list. To make ``b`` a list that has the same values as 
+``a`` you can create a new list with ``a``:
+
+>>> b = list(a)
+
+
 Why do lambdas defined in a loop with different values all return the same result?
 ----------------------------------------------------------------------------------
 
@@ -1601,6 +1620,69 @@
 13891296
 
 
+Why is the value of my default keyword argument not what I expect?
+------------------------------------------------------------------
+
+Given the following class::
+
+   from datetime import datetime
+   class A(object):
+       def __init__(self, created_time=datetime.now()):
+           self.created_time = created_time
+
+this happens:
+
+>>> first = A()
+>>> second = A()
+>>> first.created_time
+datetime.datetime(2014, 1, 16, 10, 40, 54, 33283)
+>>> second.created_time
+datetime.datetime(2014, 1, 16, 10, 40, 54, 33283)
+
+because default arguments are evaluated when the ``def`` statement is first 
+executed. For example when the class is imported. A good way to get the 
+desired behavior is to use a default argument of None and check for it, like
+this::
+
+   from datetime import datetime
+   class B(object):
+       def __init__(self, created_time=None):
+           if created_time is None:
+               created_time = datetime.now()
+           self.created_time = created_time
+
+>>> first = B()
+>>> second = B()
+>>> first.created_time
+datetime.datetime(2014, 1, 16, 10, 44, 44, 956710)
+>>> second.created_time
+datetime.datetime(2014, 1, 16, 10, 44, 51, 71311)
+
+
+Why is changing a mutable object in one instance of a class also changing it in another instance of the same class?
+-------------------------------------------------------------------------------------------------------------------
+
+Given the following class::
+
+   class A(object):
+       def __init__(self, numbers=[]):
+           self.numbers = numbers
+
+this happens:
+
+>>> first = A()
+>>> second = A()
+>>> first.numbers.append(1)
+>>> second.numbers
+[1]
+
+because variables are just names for things and because default arguments are 
+evaluated when the ``def`` statement is executed. For example, first the class
+is imported and the ``def`` statement is executed creating an instance of list. 
+After that, new instances of ``A`` have a variable ``numbers`` that is a name 
+for that instance of list.
+
+
 Modules
 =======