gistfile1.txt

from collections import defaultdict


def sum_per_date(rows):
  date_sums = defaultdict(int)
  for row in rows:
    date_sums[row['date']] += row['amount']
  return dict(date_sums)


sum_per_date([
  {'date': '2021-10-01', 'amount': 50},
  {'date': '2021-10-01', 'amount': 60},
  {'date': '2021-10-02', 'amount': 20}
])
# {
#   '2021-10-01': 110,
#   '2021-10-02': 20
# }