curl --request GET \
  --url https://api.predexon.com/v2/polymarket/volume-chart/{condition_id} \
  --header 'x-api-key: <api-key>'

{
  "condition_id": "<string>",
  "start_time": 123,
  "end_time": 123,
  "data": [
    {
      "timestamp": 123,
      "total_volume": 123,
      "yes_volume": 123,
      "no_volume": 123,
      "trades_count": 123
    }
  ]
}