import ctypes # provides low-level arrays
from array import array

class MyList:
    def __init__(self):
        self._n = 0 # count actual elements
        self._capacity = 1 # default array capacity
        self._A = self._make_array(self._capacity) # low-level array

    def __len__(self):
        # Return number of elements stored in the array.
        return self._n

    def __getitem__(self, k):
        # Return element at index k.
        if not 0 <= k < self._n:
            raise IndexError( "invalid index" )
        return self._A[k] # retrieve from array

    def append(self, obj):
        #Add object to end of the array.
        if self._n == self._capacity: # not enough room
            self._resize(2*self._capacity) # so double capacity
        self._A[self._n] = obj
        self._n += 1

    def _resize(self, c): # nonpublic utitity
        #Resize internal array to capacity c.
        B = self._make_array(c) # new (bigger) array
        for k in range(self._n): # for each existing value
            B[k] = self._A[k]
        self._A = B # use the bigger array
        self._capacity = c

    def _make_array(self, c): # nonpublic utitity Return new array with capacity c.”””
        return (c*ctypes.py_object)( ) # see ctypes documentation