curl --request POST \
  --url https://api.anysite.io/api/fred/series/observations \
  --header 'Content-Type: application/json' \
  --header 'access-token: <api-key>' \
  --data '
{
  "series_id": "<string>",
  "count": 2,
  "timeout": 300,
  "observation_start_date": "2010-01-01",
  "observation_end_date": "2023-12-31",
  "aggregation_method": "avg",
  "units": "lin"
}
'

[
  {
    "date": "<string>",
    "@type": "@fred_observation",
    "value": 123
  }
]