# 1. Introduction

A Deque (pronounced 'deck') is a double-ended queue that allows you to add or remove items from both the front and the back. It provides the flexibility of stacks and queues combined. Deques are often used in algorithms that need to add or remove items with both LIFO (Last-In-First-Out) and FIFO (First-In-First-Out) behaviors.

# 2. Implementation Steps

1. Utilize Python's inbuilt collections module which provides a deque class.

2. Define the append_left and append_right methods to add items to the front and end, respectively.

3. Define the pop_left and pop_right methods to remove items from the front and end, respectively.

4. Implement a method called is_empty to check if the deque is empty.

5. Implement a method called size to get the number of elements in the deque.

# 3. Implementation in Python

``````from collections import deque
class Deque:
def __init__(self):
# Initialize an empty deque
self.items = deque()
def append_left(self, item):
# Add an item to the front of the deque
self.items.appendleft(item)
def append_right(self, item):
# Add an item to the end of the deque
self.items.append(item)
def pop_left(self):
# Remove and return an item from the front of the deque
if not self.is_empty():
return self.items.popleft()
return None
def pop_right(self):
# Remove and return an item from the end of the deque
if not self.is_empty():
return self.items.pop()
return None
def is_empty(self):
# Check if the deque is empty
return len(self.items) == 0
def size(self):
# Return the number of items in the deque
return len(self.items)
# Test the Deque class
dq = Deque()
dq.append_left("front1")
dq.append_right("end1")
print("Popped from left:", dq.pop_left())  # Should print front1
print("Popped from right:", dq.pop_right())  # Should print end1
``````

### Output:

```Popped from left: front1
Popped from right: end1
```

### Explanation:

1. We use the deque class from Python's collections module to efficiently implement a deque.

2. The append_left method utilizes the appendleft method of the deque class to add an item to the front.

3. The append_right method utilizes the append method of the deque class to add an item to the end.

4. The pop_left method utilizes the popleft method of the deque class to remove and return an item from the front.

5. The pop_right method utilizes the pop method of the deque class to remove and return an item from the end.

6. The is_empty method checks whether the deque is empty by comparing the length of items to 0.

7. The size method returns the number of items in the deque.