///|
fn main {
  try {
    let t = @data.districts()
    println(t.feature("regions").stringify())
    let border = t.mesh(name="regions", boundary=@topo.Interior)
    assert_eq(border, {
      "type": "MultiLineString",
      "coordinates": [[[1, 0], [1, 1]]],
    })
    println(border.stringify())
  } catch {
    e => {
      println(e.to_string())
      panic()
    }
  }
}