# Problem Statement
Write a function that takes two string parameters, an IP (v4) address and a subnet mask, and returns two strings: the network block, and the host identifier.
The function does not need to support CIDR notation.
# Description
A single IP address with subnet mask actually specifies several addresses: a network block, and a host identifier, and a broadcast address. These addresses can be calculated using a bitwise AND operation on each bit.
(The broadcast address is not used in this kata.)
## Example
A computer on a simple home network might have the following IP and subnet mask:
```
IP: 192.168.2.1
Subnet: 255.255.255.0
(CIDR Notation: 192.168.2.1 /24)
```
In this example, the network block is: **192.168.2.0**. And the host identifier is: **0.0.0.1**. 
## bitwise AND 
To calculate the network block and host identifier the bits in each octet are ANDed together. When the result of the AND operation is '1', the bit specifies a network address (instead of a host address).
To compare the first octet in our example above, convert both the numbers to binary and perform an AND operation on each bit:
```
11000000 (192 in binary)
11111111 (255 in binary)
--------------------------- (AND each bit)
11000000 (192 in binary)
```
So in the first octet, '**192**' is part of the network address. The host identifier is simply '**0**'.
For more information see the [Subnetwork](http://en.wikipedia.org/wiki/Subnetwork) article on Wikipedia.
def ipv4__parser(ip_addr, mask):
    arr = [(int(p), int(m)) for p, m in zip(ip_addr.split('.'), mask.split('.'))]
    return ('.'.join(str(a & b) for a, b in arr), '.'.join(str(a & b ^ a) for a, b in arr))
def ipv4__parser(ip_addr, mask):
    arr = [(int(p), int(m)) for p, m in zip(ip_addr.split('.'), mask.split('.'))]
    return ('.'.join(str(a & b) for a, b in arr), '.'.join(str(a & b ^ a) for a, b in arr))