def invertdict(D):
    def keysof(V):
        return sorted(K for K in D.keys() if D[K] == V)
    return {V: keysof(V) for V in set(D.values())}
D = {'x': 'a', 'y': 'b', 'z': 'a'}
print(invertdict(D))

s = "Hello, world!"
s.find("world", 0, 7) + s.find("world", 5)

class D:
    __slots__ = ['a', 'b']
d = D()
d.a = 1
f = lambda attr: getattr(d, attr, '*')
print(f('a'), f('b'), f('__dict__'))

import numpy as np
a = np.array([1, 2, 3])
n1 = round(np.linalg.norm(a, ord=np.inf), 1)
n2 = round(np.linalg.norm(a, ord=1), 1)
n3 = round(np.linalg.norm(a, ord=2), 1)
print(n1, n2, n3)

6 + ~6

class D:
    __slots__ = ["a", "__dict__"]
    def __init__(self):
        self.b = 2
d = D()
d.a = 1
d.c = 3
print(sorted(d.__dict__.values()))

g = (str(i**2) for i in range(1, 4))
print("".join(g) + "".join(g))

f = lambda x: isinstance(x, int)
print(f(1), f(1.0), f(True), f(1j))

(2 << 2) + (20 >> 2)