Write `summarize(rows)` that takes a list of dicts with `"pair"`, `"amount"` (string), `"fee"` (string), converts amount/fee to floats, and returns a dict `{pair: {"volume": total_amount, "fees": total_fee}}` grouped by pair.
Required in your answer: defaultdictfloat(row
Runs via Pyodide
from collections import defaultdict
def summarize(rows):
# TODO: group by pair, sum amount as volume and fee as fees
pass
