File wide scope [Enhancement]

Any thoughts on the possibility of adding a file-wide scope to a gin config? I am thinking about the case where one may want to instantiate many instances of the same model with different parameters each time. I could through every file and prepend `model_001/` then `model_002/`, etc. everywhere but I feel there could be a better way. Or maybe add the option to parse with a given scope, e.g. `gin.parse_config_file('config.gin', scope='model_001')`. Or extend the `include` syntax as follows: `include 'path/to/another/file.gin' with scope model_001`