code: function cacheValid () {
      // false if cache result is null
      if (this.cached === null) {
          debug('view:select:collection:cacheValid:false:null', this.selectCacheKey)
          return false
      }
      // false if n does not match
      if (this.cached.n !== this.initialMaxRecordNumber) {
          debug('view:select:collection:cacheValid:false:maxRecordNumber', this.selectCacheKey)
          return false
      }
      // cache is valid
      debug('view:select:collection:cacheValid:true', this.selectCacheKey)
      return true
  }
docs: @function cacheValid
  
  check if cached value is value
  
  @returns {boolean}