This will set the value of the variable *word* to 'spam'. This idiom can be applied to lists and tuples.
+Sometimes we need to search through a collection of things. Let's look at two options: lists and dictionaries.
+
+Take the following code for example::
+
+ d = {'s': [], 'p': [], 'a': [], 'm': []}
+ l = ['s', 'p', 'a', 'm']
+
+ def lookup_dict(d):
+ return 's' in d
+
+ def lookup_list(l):
+ return 's' in l
+
+Even though both functions look identical, because *lookup_dict* is utilizing the fact that dictionaries in python are hashtables, the lookup performance between the two is very different.
+Python will have to go through each item in the list to find a matching case, which is time consuming. By analysing the hash of the dictionary finding keys in the dict can be done very quickly.
+For more information see this `StackOverflow <http://stackoverflow.com/questions/513882/python-list-vs-dict-for-look-up-table>`_ page.
+
Zen of Python
-------------