The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!

print 'Hello World'

algum_numero = 1
algum_decimal = 3.14
algum_texto = 'Hello World'
# Algum comentário

def soma_ab(a, b):
    return a + b

class Veiculo(object):
    posicao_x = 0
    posicao_y = 0

    def andar(self, x, y):
        self.posicao_x += x
        self.posicao_y += y
        return self.posicao_x, self.posicao_y

carro = Veiculo()

CONSTANTE_PI = 3.14

variavel_numerica = 12345
variavel_texto = 'um dois tres quatro'

class NomeDaClasse(object):
    atributo_publico = 'um'
    __atributo_privado = 'dois'

    def nome_do_metodo(self, variavel_um):
        # comentario
        return None

>>> True, False
(True, False)

>>> bool(True), bool(1), bool('texto')
(True, True, True)

>>> bool(False), bool(0), bool(''), bool(None)
(False, False, False, False)

>>> bool('False'), bool(-1), bool(' ') 
(True, True, True)

>>> 'texto', "texto", type('texto')
('texto', 'texto', str)

>>> u'texto com acentuação', type(u'texto')
(u'texto com acentua\xe7\xe3o', unicode)

>>> 'texto' + 'com' + 'texto'
'textocomtexto'

>>> """texto de
        muitas
         linhas"""
'texto de\n        muitas\n         linhas'

>>> u'texto mesclado: %s %s %s %s %s' % (1, '+', 1, '=', 1+1)
u'texto mesclado: 1 + 1 = 2'

>>> type(123), type(3.14), type(5+2j)
(int, float, complex)

>>> float(123), int(3.14), complex(123)
(123.0, 3, 123+0j)

>>> int('3'), float('5'), float('+inf')
(3, 5.0, inf)

>>> float('inf') - 10*1000
inf

>>> float('inf') + float('inf') + float('inf')
inf

>>> float('inf') - float('inf')
nan

>>> 1+1
2

>>> 2*2
4

>>> 3**2
9

>>> 5/2
2

>>> 5%2
1

>>> round(3.14)
3.0

>>> import math

>>> math.pi
3.141592653589793

>>> math.sqrt(16)
4.0

>>> math.sqrt(15)
3.872983346207417

>>> math.floor(3.14)
3.0

>>> math.ceil(3.14)
4.0

>>> [1,2,3] + [3,4,5,6]
[1, 2, 3, 3, 4, 5, 6]

>>> lista = []  # list()
>>> lista.append(123)
>>> lista += [456]
>>> lista
[123, 456]
>>> lista[0]
123

>>> 123 in lista
True

>>> lista.pop(123)
123

>>> 123 in lista
False

>>> (1,2,3) + (3, 4,5,6)
(1, 2, 3, 3, 4, 5, 6)

>>> tupla = ()  # tuple()
>>> tupla.append(123)
AttributeError: 'tuple' 
object has no 'append'

>>> tupla = (123, 456)
>>> tupla
(123, 456)
>>> tupla[0]
123

>>> 123 in tupla
True

>>> list(tupla)
[123, 456]

>>> dicionario = {}  # dict()
>>> cores_css = {'azul': '#0000FF', 'laranja': '#FFA500'}
>>> frutas_en = {u'maçã': 'apple', 'laranja': 'orange'}
>>> numeros = {'um': 1, 'pi': 3.14, 0: 'zero', None: None}

>>> cores_css['azul']
'#0000FF'
>>> numeros[0]
'zero'

>>> cores_css['laranja'] == frutas_en['laranja']
False

>>> numeros.keys()    # não garante ordem
['um', 0, 'pi', None]
>>> numeros.values()  # não garante ordem
[1, 'zero', 3.14, None]
>>> numeros.items()   # não garante ordem
[('um', 1), (0, 'zero'), ('pi', 3.14), (None, None)]

>>> conjunto_a = {1, 2, 3}  # set([1,2,3])
>>> conjunto_b = {3, 4, 5, 6}
>>> conjunto_a.union(conjunto_b)
{1, 2, 3, 4, 5, 6}

>>> conjunto_a.update(123)
>>> conjunto_a
{1, 2, 3, 123}

>>> 123 in conjunto_a
True

>>> True or False
True
>>> True and False
False
>>> not False
True

i = 0
while i<42:
    print i
    i += 1

coisas = {1: 'um', 'pi': 3.14, 'azul': '#00F', None: 'nada'}

for key, val in coisas.items():
    print 'Keyword:', key
    print 'Valor:', val

>>> a, b = 1, 0
>>> c = a/b
ZeroDivisionError: integer division or modulo by zero

try:
    faz_coisas_perigosas()
except FalhaEsperadaException:
    trata_falha_comum()
except:
    trata_todas_as_outras_falhas()
    raise
finally:
    limpa_o_lixo()

raise NotImplementedError('Caso não implementado')

raise RuntimeError('Deu errado.')

def nome_da_funcao():
    print u'O retorno padrão é None' 

def soma_ou_subtrai(a, b, operacao='soma'):
    if operacao == 'soma':
        return a+b
    elif operacao == 'subtracao':
        return a-b
    else:
        raise NotImplementedError('Como faz "%s"?' % operacao)

def soma(a, b):
    return a+b

def multiplicacao(a, b):
    return a*b

def faz_uma_conta(a, b, conta=soma):
    return conta(a, b)

def soma(a, b):
    return a+b

def multiplicacao(a, b):
    return a*b

def faz_contas(a, b, **contas):  # **kwargs
   for nome, funcao in contas.items():
       print 'Conta: %s %s %s' % (a, nome, b)
       print 'Resultado: %s' % funcao(a,b)

import modulo

from funcoes import soma

# funcoes.py
# coding: utf-8

def soma(a, b):
    return a+b

def subtracao(a, b):
    return a-b

def multiplicacao(a, b):
    return a*b

def divisao(a, b):
    return a/b

# print u'módulo pronto!'

main.py
funcoes.py       # <- código aqui

# main.py
from funcoes import soma

class A(object):
    a = 1      # publico
    __b = 2    # privado

    def met(self):
        print 'chamando A.met...'
        return self.a, self.__b

class B(A):
    __c = 3    # privado
   
    def __init__(self):
        # construtor
        print 'Iniciando B...'

    def met(self):
        'Imprime a e __b'
        print 'chamando B.met...'
        return super(B, self).met()

class MinhaClasse(object):
    def __init__(texto):
        self.texto = texto
    def __mul__(self, numero):
        return self.texto * numero

>>> mc = MinhaClasse(4)
>>> mc * 3
12

>>> mc1 = MinhaClasse('um')
>>> mc1 * 3
'umumum'

# coding: utf-8
from flask import Flask   # pip install flask
app = Flask(__name__)

@app.route('/')
def hello():
    return '<h1>Hello World!</h1>'

@app.route('/vezesdois/<int:numero>/')
def vezes_dois(numero):
    resposta = numero * 2
    return '<h1> %s </h1>' % str(resposta)

if __name__ == '__main__':
    # app.debug = True
    app.run()