code: function calculateBoundsFromNestedArrays (array) {
      var x1 = null, x2 = null, y1 = null, y2 = null;
  
      for (var i = 0; i < array.length; i++) {
        var inner = array[i];
  
        for (var j = 0; j < inner.length; j++) {
          var lonlat = inner[j];
  
          var lon = lonlat[0];
          var lat = lonlat[1];
  
          if (x1 === null) {
            x1 = lon;
          } else if (lon < x1) {
            x1 = lon;
          }
  
          if (x2 === null) {
            x2 = lon;
          } else if (lon > x2) {
            x2 = lon;
          }
  
          if (y1 === null) {
            y1 = lat;
          } else if (lat < y1) {
            y1 = lat;
          }
  
          if (y2 === null) {
            y2 = lat;
          } else if (lat > y2) {
            y2 = lat;
          }
        }
      }
  
      return [x1, y1, x2, y2 ];
    }
docs: /*
  Internal: Calculate an bounding box from an nested array of positions
  [
  [
  [ [lng, lat],[lng, lat],[lng, lat] ]
  ]
  [
  [lng, lat],[lng, lat],[lng, lat]
  ]
  [
  [lng, lat],[lng, lat],[lng, lat]
  ]
  ]