How to use the jsts.precision function in jsts

var newOsmBoundarySources = {}
  Object.keys(zoneCfg).forEach((zoneName) => {
    zoneCfg[zoneName].forEach((op) => {
      if (op.source === 'overpass') {
        newOsmBoundarySources[op.id] = osmBoundarySources[op.id]
      }
    })
  })

  osmBoundarySources = newOsmBoundarySources
}

var geoJsonReader = new jsts.io.GeoJSONReader()
var geoJsonWriter = new jsts.io.GeoJSONWriter()
var precisionModel = new jsts.geom.PrecisionModel(1000000)
var precisionReducer = new jsts.precision.GeometryPrecisionReducer(precisionModel)
var distZones = {}
var minRequestGap = 4
var curRequestGap = 4

var safeMkdir = function (dirname, callback) {
  fs.mkdir(dirname, function (err) {
    if (err && err.code === 'EEXIST') {
      callback()
    } else {
      callback(err)
    }
  })
}

var debugGeo = function (op, a, b, reducePrecision) {
  var result