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 clone_variable(self, vname):
      self.get_unique_name(vname)
      if vname in self.nnp_graph.variables:
          self.new_graph.variables[vname] = self.nnp_graph.variables[
              vname
          ].clone()
      elif vname in self.nnp_graph.parameters:
          self.new_graph.parameters[vname] = self.nnp_graph.parameters[
              vname
          ].clone()
  
imports: import nnabla
label_desc: Use image node_id 11 for calling the OptimizerBuilder obj's underlying member method code with example usage: obj.clone_variable(vname) without return types