# Sum of natural numbers

Write a function

*sum_natural_numbers*that takes a positive integer*n*and returns the sum of all natural numbers from 1 to*n*.```
def sum_natural_numbers(n):
```

```
# complete function here...
```

```
print(sum_natural_numbers(5)) # expected output: 15
print(sum_natural_numbers(7)) # expected output: 28
print(sum_natural_numbers(77)) # expected output: 3003
```

Python

`Setting up Python environment...`

Output