$ python3 my_queue1.py 
head =  0 , tail =  5
初期値:  [ 6 2 3 7 9 ]
取り出した要素: 6 2
head =  2 , tail =  5
キューの状態:  [ 3 7 9 ]
head =  2 , tail =  1
キューの状態:  [ 3 7 9 5 8 ]