code: def reset(self):
      self.global_mean = np.zeros(self.num_channels, dtype=self.dtype)
      self.global_var = np.zeros(self.num_channels, dtype=self.dtype)
      self.global_max = np.ones_like(self.global_mean) * float("-inf")
      self.global_min = np.ones_like(self.global_mean) * float("+inf")
      self.n_items = 0
  
imports: import numpy
  from typing import Optional, Tuple
label_desc: Use image node_id 2 for calling the DatasetMeanStdCalculator obj's underlying member method code with example usage: obj.reset() without return types