Can't access column from aggregates

For this SQL
```sql
SELECT COUNT(tab1.col1) AS cnt FROM tab1
```

How do I access `tab1.col1` that is inside the count-aggregate?

`node = parsed[0].tokens[2]` gives the `Identifier` node but I cannot proceed after that.
`node.get_real_name()` gives `COUNT` and `node.get_alias()` gives `cnt`