>>> import AtCoder.Internal.Queue qualified as Q
>>> que <- Q.new @_ @Int 3
>>> Q.capacity que
3

>>> Q.pushBack que 0 -- [0  _  _  _]
>>> Q.pushBack que 1 -- [0, 1  _  _]
>>> Q.pushBack que 2 -- [0, 1, 2  _]
>>> Q.length que
3

>>> Q.popFront que   -- [_  1, 2  _]
Just 0

>>> Q.freeze que     -- [_  1, 2  _]
[1,2]

>>> Q.readFront que 0
1

>>> Q.readFront que 1
2

>>> Q.readFront que (-1)
*** Exception: AtCoder.Internal.Queue.readFront: index out of bounds
...

>>> Q.readFront que 2
*** Exception: AtCoder.Internal.Queue.readFront: index out of bounds
...

>>> Q.readMaybeFront que (-1)
Nothing

>>> Q.readMaybeFront que 2
Nothing

>>> Q.writeFront que 0 10 -- [_ 10, 2  _]
>>> Q.writeFront que 1 20 -- [_ 10, 20 _]

>>> Q.writeFront que (-1) 777
*** Exception: AtCoder.Internal.Queue.modifyFrontM: index out of bounds
...

>>> Q.writeFront que 2 777
*** Exception: AtCoder.Internal.Queue.modifyFrontM: index out of bounds
...

>>> Q.readBack que 0
20

>>> Q.readBack que 1
10

>>> Q.readBack que (-1)
*** Exception: AtCoder.Internal.Queue.readBack: index out of bounds
...

>>> Q.readBack que 2
*** Exception: AtCoder.Internal.Queue.readBack: index out of bounds
...

>>> Q.readMaybeBack que (-1)
Nothing

>>> Q.readMaybeBack que 2
Nothing

>>> Q.writeBack que 0 200
>>> Q.writeBack que 1 100

>>> Q.writeBack que (-1) 777
*** Exception: AtCoder.Internal.Queue.modifyBackM: index out of bounds
...

>>> Q.writeBack que 2 777
*** Exception: AtCoder.Internal.Queue.modifyBackM: index out of bounds
...

>>> Q.pushFront que 10 -- [10, 100, 200  _]
>>> Q.pushFront que 1000
*** Exception: AtCoder.Internal.Queue.pushFrontST: no empty front space
...

>>> Q.unsafeFreeze que -- [10, 100, 200  _]
[10,100,200]

>>> Q.clear que        -- [_  _  _  _]
>>> Q.peekBack que
Nothing

>>> Q.popFront que
Nothing

>>> Q.popBack que
Nothing

>>> Q.pushBack que 0 -- [0  _  _  _]
>>> Q.peekBack que
Just 0

>>> Q.pushBack que 1 -- [0, 1  _  _]
>>> Q.pushBack que 2 -- [0, 1, 2  _]
>>> Q.popBack que    -- [0, 1  _  _]
Just 2

>>> Q.freeze que
[0,1]