ADD Snippet suggestions

Please suggest any code fragment you feel should be included in the scss-helpers extension for use in future releases. For instance:

Suggest _pow snippet for

```
@function pow($base, $exponent) {
$result: 1;
@for $_ from 1 through $exponent {
$result: $result * $base;
}
@return $result;
}
```

YOUR suggestion must prefixes with underscore (ex, _pow, _invert)