class_docstr: RCNN L1 loss. 
code: def __init__(self):
      super(RCNNL1LossMetric, self).__init__("RCNNL1Loss")
  
imports: import mxnet
label_desc: Use image node_id 1 to create a new RCNNL1LossMetric object from inherited base classes: mx.metric with example: obj = RCNNL1LossMetric()