code: def min_outputs(self):
      return len(self.xshapes)
  
imports: import nnabla
  import nnabla.function
  import nnabla.functions
  from nnabla.function import PythonFunction
label_desc: Use image node_id 6 for calling the ConcatenateDataGrad obj's underlying member method code with example usage: obj.min_outputs() and returns: len