code: def init(self, M, N, dtype):
      self.input = self.tensor([M, N], dtype)
      self.set_module_name("replace_nan")
  
imports: import benchmark_caffe2
  from benchmark_caffe2 import Caffe2BenchmarkBase
  from caffe2.python import core
  import operator_benchmark
label_desc: Use image node_id 1 for calling the ReplaceNaNBenchmark obj's underlying member method code with example usage: obj.init(M, N, dtype) without return types