def build_rpn_head(cfg, input_shape):
    """
    Build an RPN head defined by `cfg.MODEL.RPN.HEAD_NAME`.
    """
    name = cfg.MODEL.RPN.HEAD_NAME
    return RPN_HEAD_REGISTRY.get(name)(cfg, input_shape)

    Build an RPN head defined by `cfg.MODEL.RPN.HEAD_NAME`.
    
video_chat_with_MOSS/models/grit_src/third_party/CenterNet2/detectron2/modeling/proposal_generator/rpn.py