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 __init__(self, nnp_graph):
      self.nnp_graph = nnp_graph
      self.token_list = []
      self.new_graph = nn.graph_def.ProtoNetwork(
          self.nnp_graph.owner(),
          self.nnp_graph.name,
          self.nnp_graph.batch_size,
      )
      self.names = {}
  
imports: import nnabla
label_desc: Use image node_id 1 to create a new OptimizerBuilder object  with example: obj = OptimizerBuilder(nnp_graph)