docs: function ProtoComputed (observables, lambda, opts) {
    if (!Array.isArray(observables)) {
      observables = [observables]
    }
    this.values = []
    this.releases = []
    this.computedValue = null
    this.outputValue = null
    this.inner = null
    this.updating = false
    this.live = false
    this.initialized = false
    this.listeners = []
    this.observables = observables
    this.lambda = lambda
    this.opts = opts
    this.comparer = opts && opts.comparer || null
  
    // when true, don't expand nested observables, just treat as values
    this.passthru = opts && opts.passthru || null
  
    this.context = opts && opts.context || {}
    this.boundOnUpdate = this.onUpdate.bind(this)
    this.boundUpdateNow = this.updateNow.bind(this)
    this.boundUnlisten = this.unlisten.bind(this)
  }