A happy number is a number defined by the following process: Starting with any positive integer,
replace the number with the sum of the squares of its digits, and repeat the process until the number either equals 1
(where it will stay), or it loops endlessly in a cycle that does not include 1.
Those numbers for which this process ends in 1 are happy numbers, while those that do not end in 1 are unhappy numbers (or sad numbers).

For example, 19 is happy, as the associated sequence is:
1^2 + 9^2 = 82
8^2 + 2^2 = 68
6^2 + 8^2 = 100
1^2 + 0^2 + 0^2 = 1

For example, 21 is happy, as the associated sequence is:
1^2 + 2^2 = 5
5^2 = 25
2^2 + 5^2 = 29
2^2 + 9^2 = 85
8^ + 5^ = 89
8^ + 9^ = 89

On the other hand, 4 is unhappy, as the associated sequence is:
4^2 = 16
1^2 + 6^2 = 37
3^2 + 7^2 = 58
5^2 + 8^2 = 89
8^2 + 9^2 = 145
1^2 + 4^2 + 5^2 = 42
4^2 + 2^2 = 20
2^2 + 0^2 = 4

The first five happy numbers are 1, 7, 10, 13, 19.

Print the happy numbers up to 1,000. Hint: There are 143.

###Testing
```bash
pipenv install 
pipenv shell
cd test
pytest```