protected _init(silent: boolean): void {
    let levels: number
    let inside_padding: number
    if (every(this.factors as any, isString)) {
      levels = 1;
      [this._mapping, inside_padding] = map_one_level(this.factors as string[], this.factor_padding)
    } else if (every(this.factors as any, (x) => isArray(x) && x.length == 2 && isString(x[0]) && isString(x[1]))) {
      levels = 2;
      [this._mapping, this.tops, inside_padding] = map_two_levels(this.factors as [string, string][], this.group_padding, this.factor_padding)
    } else if (every(this.factors as any, (x) => isArray(x) && x.length == 3  && isString(x[0]) && isString(x[1]) && isString(x[2]))) {
      levels = 3;
      [this._mapping, this.tops, this.mids, inside_padding] = map_three_levels(this.factors as [string, string, string][], this.group_padding, this.subgroup_padding, this.factor_padding)
    } else
      throw new Error("???")

    let start = 0
    let end = this.factors.length + inside_padding

    if (this.range_padding_units == "percent") {
      const half_span = (end - start) * this.range_padding / 2
      start -= half_span
      end += half_span
    } else {
      start -= this.range_padding
      end += this.range_padding
    }

    this.setv({start, end, levels}, {silent})

    if (this.bounds == "auto")
      this.setv({bounds: [start, end]}, {silent: true})
  }

 compute_indices(_source: DataSource): number[] | null {
   if (this.indices != null && this.indices.length >= 0) {
     if (every(this.indices, isInteger))
       return this.indices
     else {
       logger.warn(`IndexFilter ${this.id}: indices should be array of integers, defaulting to no filtering`)
       return null
     }
   } else {
     logger.warn(`IndexFilter ${this.id}: indices was not set, defaulting to no filtering`)
     return null
   }
 }

 compute_indices(source: ColumnarDataSource): number[] | null {
   const booleans = this.booleans
   if (booleans != null && booleans.length > 0) {
     if (every(booleans, isBoolean)) {
       if (booleans.length !== source.get_length()) {
         logger.warn(`BooleanFilter ${this.id}: length of booleans doesn't match data source`)
       }
       return range(0, booleans.length).filter((i) => booleans[i] === true)
     } else {
       logger.warn(`BooleanFilter ${this.id}: booleans should be array of booleans, defaulting to no filtering`)
       return null
     }
   } else {
     if (booleans != null && booleans.length == 0)
       logger.warn(`BooleanFilter ${this.id}: booleans is empty, defaulting to no filtering`)
     else
       logger.warn(`BooleanFilter ${this.id}: booleans was not set, defaulting to no filtering`)
     return null
   }
 }

 const active = (() => { switch (this.model.click_policy) {
   case "none": return true
   case "hide": return every(item.renderers, r => r.visible)
   case "mute": return every(item.renderers, r => !r.muted)
 } })()