By @dnl0x00

Non-keyworded, variable length argument list.

Here’s an example which shows how to pass variable length arguments and get the values.

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def g(a, *args):
    b, c = args
    assert a == 1

def f(a, *args):
    g(a, *args)

f(1, 2, 3)

for … else

Did you know that the for loop in Python has an else? The else part is executed if the for was not quit via a break.

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def chk(n):
    for i in range(60):
        if i == n:
            break
    else:
        # this code is executed only if the for loop was
        # not quit via break
        return 1
    return 0

assert chk(30) == 0
assert chk(90) == 1

toString for Python objects

Want a toString like in Java for objects? Implement __repr__.

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class X:
    def __repr__(self):
       return "This is X"

x = X()
print(x)

Expanding tuples into arguments

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def f(a, b, c):
    pass

params = (1, 2, 3)
f(*params)

() operator in Python

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class X:
    def __call__(self, x):
       return x + 1

f = X()
print(f(5))  # print the value 6

fileinput

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import filename
for line in fileinput.input():
    process(line)

“This iterates over the lines of all files listed in sys.argv[1:], defaulting to sys.stdin if the list is empty. If a filename is ‘-‘, it is also replaced by sys.stdin.”

source: https://docs.python.org/2/library/fileinput.html