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import heapq
from typing import Union


class PriorityQueue:
    """A priority queue implementation based on heapq"""

    insertion_count = 0

    def __init__(self) -> None:

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from collections import deque
from typing import Any


class Stack:
    """A stack implementation based on deque"""

    def __init__(self) -> None:
        """Initialize the stack as an empty deque"""
        self.items = deque()

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    def is_empty(self) -> bool:
        """Returns True is the stack is empty"""
        return not self.items

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    def push(self, item: Any) -> None:
        """Add an item to the top of the stack"""
        self.items.append(item)

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    def pop(self) -> Any:
        """Return and remove the item at the top of the stack"""
        if self.is_empty():
            return None
        return self.items.pop()

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    def peek(self) -> Any:
        """Return the item at the top of the stack"""
        if self.is_empty():
            return None
        return self.items[-1]

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    def size(self) -> int:
        """Return the number of items in the stack"""
        return len(self.items)

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from collections import deque
from typing import Any


class Stack:
    """A stack implementation based on deque"""

    def __init__(self) -> None:
        """Initialize the stack as an empty deque"""
        self.items = deque()

wanderindev

from collections import deque
from typing import Any


class Queue:
    """A queue implementation based on deque"""

    def __init__(self) -> None:
        """Initialize the queue as an empty deque"""
        self.items = deque()

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    def is_empty(self) -> bool:
        """Returns True is the queue is empty"""
        return not self.items