curl --request PATCH \
  --url https://app.getcensus.com/api/v1/sources/{source_id}/filter_segments/{segment_id} \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "name": "priority accounts",
  "molecules": [
    {
      "attribute": "last_seen_at",
      "attribute_type": "property",
      "operator": "isnotnull",
      "value": "id"
    }
  ]
}
'

{
  "status": "updated",
  "data": {
    "type": "segment",
    "id": 18,
    "name": "priority accounts",
    "model_id": 9,
    "dataset_id": 12,
    "query": "SELECT * FROM (\n  SELECT 1 AS id, 'Planet Express'::text AS company_name\n) AS census_1d19740e93f711b22efaea201fcf3f8f\nWHERE (\"id\" IS NOT NULL )\n",
    "record_count": 12540,
    "created_at": "2021-10-20T02:43:07.120Z",
    "updated_at": "2021-10-20T02:50:35.477Z",
    "resource_identifier": "segment:priority-accounts",
    "molecules": [
      {
        "attribute": "last_seen_at",
        "attribute_type": "property",
        "operator": "isnotnull",
        "value": "id"
      }
    ],
    "filter_segment_source_object_id": 32,
    "cohorts": [
      {
        "id": 18,
        "name": "Treatment A",
        "percentage": 50,
        "is_control": true,
        "created_at": "2021-10-20T02:43:07.120Z",
        "resource_identifier": "cohort:treatment-a"
      }
    ]
  }
}