Python-сообщество

def list_function(x):
    i = 0
    for i in x:
        x[i] = x[i] * 2
    return x

n = [1, 2, 3]
list_function(n)
print (n)

for i in x:
    x[i] = # ненененене
              # i - это не индекс, это [b]сам элемент[/b]

def list_function(x):
    for i in x:
        print  i*2
n = [1, 2, 3]
list_function(n)

2
4
6

>>> def mul2(seq):
...     return (i * 2 for i in seq)
... 
>>> list(mul2([1, 2, 3]))
[2, 4, 6]
>>>

def get_list_numbers(number_list):
    print([row * row for row in number_list])
check_numbers = [1,2,3]
get_list_numbers(check_numbers)

def list_function(x):
    for i in range(len(x)):
        x[i] *= 2
    return x

In [1]: lst = [1, 2, 3]
In [2]: map(lambda x: x * 2, lst)
Out[2]: [2, 4, 6]
In [3]: [i * 2 for i in lst]
Out[3]: [2, 4, 6]