{
  "$schema": "urn:prism:schema:v1:spec",
  "title": "Weekly visits by source",
  "data": {
    "values": [
      {"week": 1, "source": "organic", "visits": 1200},
      {"week": 2, "source": "organic", "visits": 1290},
      {"week": 3, "source": "organic", "visits": 1330},
      {"week": 4, "source": "organic", "visits": 1410},
      {"week": 1, "source": "paid", "visits": 600},
      {"week": 2, "source": "paid", "visits": 730},
      {"week": 3, "source": "paid", "visits": 720},
      {"week": 4, "source": "paid", "visits": 800},
      {"week": 1, "source": "referral", "visits": 220},
      {"week": 2, "source": "referral", "visits": 245},
      {"week": 3, "source": "referral", "visits": 280},
      {"week": 4, "source": "referral", "visits": 310}
    ]
  },
  "mark": "line",
  "encoding": {
    "x": {"field": "week", "type": "quantitative"},
    "y": {"field": "visits", "type": "quantitative"},
    "color": {"field": "source", "type": "nominal"}
  }
}