text: import torch
  
  from e3nn import o3
  from e3nn.util.jit import compile_mode
  
  
  @compile_mode('trace')
  class Identity(torch.nn.Module):
      r"""Identity operation
  
      Parameters
      ----------
      irreps_in : `e3nn.o3.Irreps`
  
      irreps_out : `e3nn.o3.Irreps`
      """
      def __init__(self, irreps_in, irreps_out):
          super().__init__()
  
          self.irreps_in = o3.Irreps(irreps_in).simplify()
          self.irreps_out = o3.Irreps(irreps_out).simplify()
  
          assert self.irreps_in == self.irreps_out
  
          output_mask = torch.cat([
              torch.ones(mul * (2 * l + 1))
              for mul, (l, _p) in self.irreps_out
          ])
          self.register_buffer('output_mask', output_mask)
  
      def __repr__(self):
          return f"{self.__class__.__name__}({self.irreps_in} -> {self.irreps_out})"
  
      def forward(
              # pylint: disable=no-self-use
              self, features):
          """evaluate
          """
          return features
  