Update queue.py

Removed the first as it became unessary because __init__ itself makes a deque object
Made the deque object as private so as to protect from unessary alteration from users

Author: Joe Green

algorithms/data_structures/queue.py

@@ -15,18 +15,17 @@
 
 
 class Queue:
-    queue_list = deque([])
 
     def __init__(self):
-        self.queue_list = deque([])
+        self._queue_list = deque([])
 
     def add(self, value):
         """
         Add element as the last item in the Queue.
 
         Worst Case Complexity:  O(1)
         """
-        self.queue_list.append(value)
+        self._queue_list.append(value)
 
     def remove(self):
         """
@@ -35,20 +34,20 @@ def remove(self):
         Worst Case Complexity:  O(1)
         """
 
-        return self.queue_list.popleft()
+        return self._queue_list.popleft()
 
     def is_empty(self):
         """
         Returns a boolean indicating if the Queue is empty.
 
         Worst Case Complexity:  O(1)
         """
-        return not len(self.queue_list)
+        return not len(self._queue_list)
 
     def size(self):
         """
         Return size of the Queue.
 
         Worst Case Complexity:  O(1)
         """
-        return len(self.queue_list)
+        return len(self._queue_list)