class_docstr: This class handles the parser event from opt_parser.
  When a target statement is matched, an event is triggered,
  we collected necessary information from this event and construct
  the branches as what we want to understand.
code: def rf_add(self, op_list):
      branch = Branch()
      branch.x = None
      branch.bias = None
      branch.add2 = op_list[1]
      reshape = op_list[0]
      if reshape.outputs[0] == branch.add2.inputs[0]:
          branch.x = reshape
      elif reshape.outputs[0] == branch.add2.inputs[1]:
          branch.bias = reshape
      branch.outputs = branch.add2.outputs
      return branch
  
imports: import nnabla
label_desc: Use image node_id 8 for calling the OptimizerBuilder obj's underlying member method code with example usage: obj.rf_add(op_list) and returns: branch