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+\section{\module{collections} ---
+ High-performance datatypes}
+
+\declaremodule{standard}{collections}
+\modulesynopsis{High-performance datatypes}
+\moduleauthor{Raymond Hettinger}{python@rcn.com}
+\sectionauthor{Raymond Hettinger}{python@rcn.com}
+\versionadded{2.4}
+
+
+This module implements high-performance datatypes. Currently, the
+only datatype is a deque. Future additions may include B-trees
+and Fibonacci heaps.
+
+\begin{funcdesc}{deque}{\optional{iterable}}
+ Returns a new deque objected initialized left-to-right (using
+ \method{append()}) with data from \var{iterable}. If \var{iterable}
+ is not specified, the new deque is empty.
+
+ Deques are a generalization of stacks and queues. They support
+ thread-safe, memory efficient appends and pops from either side of the
+ deque with approximately the same performance in either direction.
+ \versionadded{2.4}
+\end{funcdesc}
+
+Deque objects support the following methods:
+
+\begin{methoddesc}{append}{x}
+ Add \var{x} to the right side of the deque.
+\end{methoddesc}
+
+\begin{methoddesc}{appendleft}{x}
+ Add \var{x} to the left side of the deque.
+\end{methoddesc}
+
+\begin{methoddesc}{clear}{}
+ Remove all elements from the deque leaving it with length 0.
+\end{methoddesc}
+
+\begin{methoddesc}{pop}{}
+ Remove and return an element from the right side of the deque.
+ If no elements are present, raises a \exception{LookupError}.
+\end{methoddesc}
+
+\begin{methoddesc}{popleft}{}
+ Remove and return an element from the left side of the deque.
+ If no elements are present, raises a \exception{LookupError}.
+\end{methoddesc}
+
+In addition to the above, deques support iteration, membership testing
+using the \keyword{in} operator, \samp{len(d)}, \samp{copy.copy(d)},
+\samp{copy.deepcopy(d)}, and pickling.
+
+Example:
+
+\begin{verbatim}
+>>> from collections import deque
+>>> d = deque('ghi') # make a new deque with three items
+>>> for elem in d: # iterate over the deque's elements
+ print elem.upper()
+
+
+G
+H
+I
+>>> d.append('j') # add a new entry to the right side
+>>> d.appendleft('f') # add a new entry to the left side
+>>> d # show the representation of the deque
+deque(['f', 'g', 'h', 'i', 'j'])
+>>> d.pop() # return and remove the rightmost item
+'j'
+>>> d.popleft() # return and remove the leftmost item
+'f'
+>>> list(d) # list the contents of the deque
+['g', 'h', 'i']
+>>> 'h' in d # search the deque
+True
+>>> d.__init__('jkl') # use __init__ to append many elements at once
+>>> d
+deque(['g', 'h', 'i', 'j', 'k', 'l'])
+>>> d.clear() # empty the deque
+>>> d.pop() # try to pop from an empty deque
+
+Traceback (most recent call last):
+ File "<pyshell#6>", line 1, in -toplevel-
+ d.pop()
+LookupError: pop from an empty deque
+\end{verbatim}