code: def step(self):
      for param in self.params:
          if param.grad is None:
              continue
          param -= self.lr * param.grad
          param.grad = None
  
imports: import typing
  import torch
  from fate.arch.context import Context
  from fate.arch.protocol.mpc.common.encoding import IgnoreEncodings
  from fate.arch.protocol.mpc.mpc import FixedPointEncoder
  from fate.arch.trace import auto_trace
label_desc: Use image node_id 2 for calling the SSHEOptimizerSGD obj's underlying member method code with example usage: obj.step() without return types