code: def min_inputs(self):
      return 1
  
imports: import nnabla
  import nnabla.function
  import nnabla.functions
  from nnabla.function import PythonFunction
label_desc: Use image node_id 5 for calling the ConcatenateDataGrad obj's underlying member method code with example usage: obj.min_inputs() and returns: int