code: def resolve_foreign_keys(object, map)
        object.foreign_keys.each do |property|
          value = object[property]
          if value
            if map.key?(value)
              object[property] = map[value]
            else
              raise Errors::MissingDatabaseIdError, "couldn't resolve foreign key: #{property} #{value}"
            end
          end
        end
      end
docs: Resolves an object's foreign keys from object IDs to database IDs.
  
   @param [Object] an object
   @param [Hash] a map from object ID to database ID
   @raises [Pupa::Errors::MissingDatabaseIdError] if a foreign key cannot be
     resolved