curl --request PATCH \
  --url https://api.example.com/api/playground/sessions/{session_id}/data \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "updates": [
    {
      "row_index": 1,
      "column": "<string>",
      "value": "<unknown>"
    }
  ]
}
'

{
  "updated": 123,
  "row_count": 123,
  "column_count": 123
}