Bus List in python

bus_list.py

from collections.abc import Iterable


class BusList(list):
    """ Bus (FIFO) list
    """

    def __init__(self, *args):
        self._max_length = 0
        for arg in args:
            if isinstance(arg, int):
                self._max_length = arg
            elif isinstance(arg, Iterable):
                super().__init__(arg)

    def _bus_out(self, index=0):
        if self._max_length > 0 and len(self) == self._max_length:
            self.pop(min(index, len(self)-1))

    def append(self, value):
        self._bus_out()
        super().append(value)

    def insert(self, index, value):
        self._bus_out()
        super().insert(index, value)

test_bus_list.py

from bus_list import BusList

bl = BusList(4, [1, 2, 3, 4])

print(bl)

for n in range(5, 10):
    bl.append(n)
    print(bl)

"""
RESULT: 

[1, 2, 3, 4]
[2, 3, 4, 5]
[3, 4, 5, 6]
[4, 5, 6, 7]
[5, 6, 7, 8]
[6, 7, 8, 9]
"""