class_docstr: Mocks Faster RCNN Network
code: def _build(self, image, gt_boxes=None, is_training=False):
      w = tf.get_variable("w", initializer=[2.5, 3.0], trainable=True)
      return {"w": w}
  
imports: import sonnet
  import tempfile
  import tensorflow
  from easydict import EasyDict
  from luminoth.train import run
  from luminoth.models import get_model
  from luminoth.utils.config import get_model_config, load_config_files, get_base_config
label_desc: Use image node_id 2 for calling the MockFasterRCNN obj's underlying member method code with example usage: obj._build(image, gt_boxes, is_training) and returns: dict