------
## 最终结论
```python
import re

def text_match_one(s):
    if re.match(r'a+b+', s):
        return 'Found a match!'
    else:
        return 'Not matched!'

# Test cases
assert text_match_one("ac") == ('Not matched!')
assert text_match_one("dc") == ('Not matched!')
assert text_match_one("abba") == ('Found a match!')
```