Function

    def my_function(name):
        return 'hello {}.'.format(name)

    def do_nothing():
        pass

    def cube(x):
        'input number, return cubic volume of input'
        return x**3

    def triangular_sum(n):
        '''input stop number "n"
        return sum 1 + 2 + 3 + ... + n
        mathematics approach, O(1)'''
        return n*(n+1) // 2

    help(cube)
    # some description on cube function

    dir()
    # will return all class/module/function that imported
    # __builtins__, __doc__, __name__, __package__
    # this 4 are standard python3's class

    import test

    print(test.cube(4))
    # get: 64

    import test as m

    print(m.cube(5))
    # get:125

    ts = m.triangular_sum
    print(ts(10))
    # get: 55

    from test import *

    print(cube(7))
    # get: 343

    def add(n, a=1):
        '''add a to n, add 1 in case no a input'''
        return n+a

    print(add(5,5))    # 10
    print(add(6))      #  7

    def sum(*args):
        '''sum all arguments'''
        out = 0
        for i in args:
            out += i
        return out

    print(sum(1,3,5,7,9))
    # get: 25


    def card(**dk):
        '''print card's point'''
        for c in dk:
            print('{:5} = {:2}'.format(c,dk[c]))

    card(a=1, jack=11, queen=12, king=13)
    # will return this:
    # a     =  1
    # king  = 13
    # queen = 12
    # jack  = 11