<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def get_multifile_object_child_location(self, parent_item_prefix: str, child_name: str) -> str: """ Implementation of the parent abstract method. In this mode the attribute is a file inside the parent object folder :param parent_item_prefix: the absolute file prefix of the parent item. :return: the file prefix for this attribute """

        check_var(parent_item_prefix, var_types=str, var_name='parent_item_prefix')
        check_var(child_name, var_types=str, var_name='item_name')

        # assert that folder_path is a folder
        if not isdir(parent_item_prefix):
            raise ValueError(
                'Cannot get attribute item in non-flat mode, parent item path is not a folder : ' + parent_item_prefix)
        return join(parent_item_prefix, child_name)