def merge_cfg_from_file(cfg_filename):
    """Load a yaml config file and merge it into the global config."""
    with open(cfg_filename, 'r') as f:
        yaml_cfg = AttrDict(load_cfg(f))
    _merge_a_into_b(yaml_cfg, __C)
Load a yaml config file and merge it into the global config.
detectron/core/config.py