class_docstr: Class implementing SimpleImputer operators in PyTorch.
code: def forward(self, x):
      if self.is_nan:
          result = torch.where(
              torch.isnan(x), self.replace_values.expand(x.shape), x
          )
          if self.do_mask:
              return result
          return torch.index_select(result, 1, self.mask)
      else:
          return torch.where(
              torch.eq(x, self.missing_values),
              self.replace_values.expand(x.shape),
              x,
          )
  
file_path: hummingbird/hummingbird/ml/operator_converters/_imputer_implementations.py
imports: import torch
  import numpy
  from ._physical_operator import PhysicalOperator
  from .None import constants
label_desc: Use image node_id 2 for calling the SimpleImputer obj's underlying member method code with example usage: obj.forward(x) and returns: torch, torch, result