#### Queue by Two Stacks

p
```"""Queue implementation using two stacks"""

from collections.abc import Iterable
from typing import Generic, TypeVar

_T = TypeVar("_T")

class QueueByTwoStacks(Generic[_T]):
def __init__(self, iterable: Iterable[_T] | None = None) -> None:
"""
>>> QueueByTwoStacks()
Queue(())
>>> QueueByTwoStacks([10, 20, 30])
Queue((10, 20, 30))
>>> QueueByTwoStacks((i**2 for i in range(1, 4)))
Queue((1, 4, 9))
"""
self._stack1: list[_T] = list(iterable or [])
self._stack2: list[_T] = []

def __len__(self) -> int:
"""
>>> len(QueueByTwoStacks())
0
>>> from string import ascii_lowercase
>>> len(QueueByTwoStacks(ascii_lowercase))
26
>>> queue = QueueByTwoStacks()
>>> for i in range(1, 11):
...     queue.put(i)
...
>>> len(queue)
10
>>> for i in range(2):
...   queue.get()
1
2
>>> len(queue)
8
"""

return len(self._stack1) + len(self._stack2)

def __repr__(self) -> str:
"""
>>> queue = QueueByTwoStacks()
>>> queue
Queue(())
>>> str(queue)
'Queue(())'
>>> queue.put(10)
>>> queue
Queue((10,))
>>> queue.put(20)
>>> queue.put(30)
>>> queue
Queue((10, 20, 30))
"""
return f"Queue({tuple(self._stack2[::-1] + self._stack1)})"

def put(self, item: _T) -> None:
"""
Put `item` into the Queue

>>> queue = QueueByTwoStacks()
>>> queue.put(10)
>>> queue.put(20)
>>> len(queue)
2
>>> queue
Queue((10, 20))
"""

self._stack1.append(item)

def get(self) -> _T:
"""
Get `item` from the Queue

>>> queue = QueueByTwoStacks((10, 20, 30))
>>> queue.get()
10
>>> queue.put(40)
>>> queue.get()
20
>>> queue.get()
30
>>> len(queue)
1
>>> queue.get()
40
>>> queue.get()
Traceback (most recent call last):
...
IndexError: Queue is empty
"""

# To reduce number of attribute look-ups in `while` loop.
stack1_pop = self._stack1.pop
stack2_append = self._stack2.append

if not self._stack2:
while self._stack1:
stack2_append(stack1_pop())

if not self._stack2:
raise IndexError("Queue is empty")
return self._stack2.pop()

if __name__ == "__main__":
from doctest import testmod

testmod()
```