Question: Suppose I have a list:

```
lst = [0, 1, 0, 0]

```

How can I make python interpret this list as a binary number 0100 so that `2*(0100)` gives me `01000`?

The only way that I can think of is to first make a function that converts the "binary" elements to corresponding integers(to base 10) and then use bin() function..

Is there a better way?

Answer: 
You can use [bitwise operators](https://wiki.python.org/moin/BitwiseOperators) like this:

```
>>> lst = [0, 1, 0, 0]
 >>> bin(int(''.join(map(str, lst)), 2) << 1)
'0b1000'

```
You can use this code for concatenating the list elements:

```
x=[0, 1, 0, 0]
b=''.join(map(str,x))
print(b)

```

Output:

```
C:\python\prog>python trying.py

0100

```