collections.deque()
collections.deque() is a Python function in the Collections Module category. Returns a double-ended queue (deque) with efficient O(1) appends/pops from both ends. The syntax is collections.deque([iterable], maxlen=None). Parameters: iterable — initial items. Returns: Deque object. A typical example: from collections import deque
d = deque([1,2,3], maxlen=5)
d.append(4); d.appendleft(0)
list(d) # [0,1,2,3,4]. A close sibling is deque.append(), which adds x to the right side of the deque. A close sibling is deque.appendleft(), which adds x to the left side of the deque. A close sibling is deque.pop(), which removes and returns the rightmost element. Raises IndexError if empty. A close sibling is deque.popleft(), which removes and returns the leftmost element. Raises IndexError if empty. More about this category: Specialized container datatypes — deque, Counter, defaultdict, namedtuple, OrderedDict. For a broader walkthrough, read the Collections Module guide. Related Collections Module entries: deque.append(), deque.appendleft(), deque.pop(), deque.popleft(), deque.extend(), deque.extendleft().