python declare array of size n
>>> n = 5 #length of list
>>> list = [None] * n #populate list, length n with n entries "None"
>>> print(list)
[None, None, None, None, None]
>>> list.append(1) #append 1 to right side of list
>>> list = list[-n:] #redefine list as the last n elements of list
>>> print(list)
[None, None, None, None, 1]
>>> list.append(1) #append 1 to right side of list
>>> list = list[-n:] #redefine list as the last n elements of list
>>> print(list)
[None, None, None, 1, 1]
>>> list.append(1) #append 1 to right side of list
>>> list = list[-n:] #redefine list as the last n elements of list
>>> print(list)
[None, None, 1, 1, 1]