docs: function del(id, callback) {
  
      callback = callback || emptyFn
  
      if (typeof callback !== 'function') {
        throw new TypeError('callback must be a function or empty')
      }
  
      self.emit('delete', id)
      var query = {}
      query[ options.idProperty ] = id
      deleteMany(query, function() {
        self.emit('afterDelete', '' + id)
        callback(undefined)
      })
    }