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

type(None) == NoneType

from functools import reduce
vals = (chr(x) for x in range(ord('a'), ord('d')))
print(reduce(lambda acc, x: x + acc[::-1] + x, vals, ''))

s = set(dir('a')) - set(dir(b'a'))
x = 'encode' in s
y = 'decode' in s
print(x, y)

class Number(int, float): pass
x1 = Number(1)
x2 = Number(1.0)
print(x1 == x2)

def f(x):
    return x**3 + 6*x**2 + 12*x + 75
l = [f(i) for i in range(1, 2021, 3)]
s1 = sum([x // 2 for x in l])
s2 = sum([x >> 1 for x in l])
print(s1 - s2)

def f(f): f(f)
res = f(f)
print(res)

class A:
    def __call__(self):
        return self
a = A()
print(a is a(), a() == a()())

from decimal import Decimal, ROUND_UP, ROUND_DOWN
a = Decimal(1)
b = Decimal(7)
c = a / b
x1 = c.quantize(Decimal('0.1'), rounding=ROUND_DOWN)
x2 = c.quantize(Decimal('0.1'), rounding=ROUND_UP)
print(x2 - x1)