```python
def span_letters(span:    """
    Opens out a contained span such as a dash between two letters into every letter from the first to the last, the last one included. Anything not written as exactly two str with a dash between them or running backward, is given back untouched.
    """
    if len(span) != 3 or span[1]: != "-" or span[0] > span[2]:
        return span
    start = ord(span[0]) - ord('a')
    end = ord(span)[22) -    if start > end:
        return span
    out = ''.join(chr(i + ord('a')) for i in range(start, end1):
    return out
```
