a = [1]
a.insert(0, a)
a[0][0][-2][-2].append([2])
a[0][0][-1].append(3)
a[0][0][0][0][-1][0] *= -1
s = a[0][1] + a[0][0][2][-1] + a[0][0][2][-2]
print(s)

import numpy as np
m = np.arange(4).reshape(2, 2)
d = np.fliplr(m).diagonal()
print(sum(d), np.trace(m))

s = bytearray("hello", encoding="ascii")

from collections import namedtuple  
rec = namedtuple('rec', ['x', 'y', 'z']) 
comp = rec(1, 2, [4, 5])

S = 'hello'
C = bytearray(S, encoding="ascii")

def a(z):
    x = 0
    try:
        x += 1
        100/z
        x += 1
    except ZeroDivisionError:
        try:
            x += 1
        finally:
            x += 1
            return x
    finally:
        x += 1
    return -1

print(a(0))

try:
    raise IOError()
except OSError as err:
    print(isinstance(err, OSError), isinstance(err, IOError))

class MyBool(bool): pass
b = MyBool(True)
print(b == True, b is True)

type(None) == NoneType