===== ISTEM =====
Using the `trimmed_mean` function from Python's standard `statistics` module, write `robust_average(values)` that returns the 10% trimmed mean of a list of numbers.

===== HAM YANIT =====
> **Note:** As of Python 3.13, Python's standard `statistics` module does not have a built-in `trimmed_mean` function (unlike SciPy, which provides `scipy.stats.trim_mean`). 

If your environment or test harness provides a mocked or extended `trimmed_mean` in `statistics`, the function would be written like this:

```python
from statistics import trimmed_mean

def robust_average(values):
    """
    Returns the 10% trimmed mean of a list of