code: 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)
      })
    }
docs: Deletes one entity. Emits a 'delete' event. Returns an error if the
  object can not be found or if the ID property is not present.
  
  @param {Object} object to delete
  @param {Function} callback (optional)
  @api public