Document , fixes RafeKettler#24

magicmethods.markdown

@@ -422,7 +422,7 @@ Without any more wait, here are the magic methods that containers use:
 :    Defines behavior for when an item is accessed, using the notation `self[key]`. This is also part of both the mutable and immutable container protocols. It should also raise appropriate exceptions: `TypeError` if the type of the key is wrong and `KeyError` if there is no corresponding value for the key.
 
 `__setitem__(self, key, value)`
-:    Defines behavior for when an item is assigned to, using the notation `self[key] = value`. This is part of the mutable container protocol. Again, you should raise `KeyError` and `TypeError` where appropriate.
+:    Defines behavior for when an item is assigned to, using the notation `self[nkey] = value`. This is part of the mutable container protocol. Again, you should raise `KeyError` and `TypeError` where appropriate.
 
 `__delitem__(self, key)`
 :    Defines behavior for when an item is deleted (e.g. `del self[key]`). This is only part of the mutable container protocol. You must raise the appropriate exceptions when an invalid key is used.
@@ -436,6 +436,9 @@ Without any more wait, here are the magic methods that containers use:
 `__contains__(self, item)`
 :    `__contains__` defines behavior for membership tests using `in` and `not in`. Why isn't this part of a sequence protocol, you ask? Because when `__contains__` isn't defined, Python just iterates over the sequence and returns `True` if it comes across the item it's looking for.
 
+`__missing__(self, key)`
+:    `__missing__` is used in subclasses of `dict`. It defines behavior for whenever a key is accessed that does not exist in a dictionary (so, for instance, if I had a dictionary `d` and said `d["george"]` when `"george"` is not a key in the dict, `d.__missing__("george")` would be called).
+
 ####An example####
 
 For our example, let's look at a list that implements some functional constructs that you might be used to from other languages (Haskell, for example).

magicmethods.tex

@@ -371,6 +371,8 @@ \subsection{The magic behind containers}
 Called to implement behavior for the \code{reversed()} built in function. Should return a reversed version of the list.
 \item[\code{__contains__(self, item)}]
 \code{__contains__} defines behavior for membership tests using \code{in} and \code{not in}. Why isn't this part of a sequence protocol, you ask? Because when \code{__contains__} isn't defined, Python just iterates over the sequence and returns \code{True} if it comes across the item it's looking for.
+\item[\code{__missing__(self, key)}]
+\code{__missing__} is used in subclasses of \code{dict}. It defines behavior for whenever a key is accessed that does not exist in a dictionary (so, for instance, if I had a dictionary \code{d} and said \code{d["george"]} when \code{"george"} is not a key in the dict, \code{d.__missing__("george")} would be called).
 
 \end{description}